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200-125 Exam Answer Part 1.1 – CCNA Cisco Certified Network Associate CCNA (v3.0)

1. A network administrator is verifying the configuration of a newly installed host by establishing an FTP connection to a remote server. What is the highest layer of the protocol stack that the network administrator is using for this operation?

A. application

B. presentation

C. session

D. transport

E. internet

F. data link

Explanation/Reference:
FTP belongs to Application layer and it is also the highest layer of the OSI model. Explanation/Reference

2. A network interface port has collision detection and carrier sensing enabled on a shared twisted pair network. From this statement, what is known about the network interface port?

A. This is a 10 Mb/s switch port.

B. This is a 100 Mb/s switch port.

C. This is an Ethernet port operating at half duplex.

D. This is an Ethernet port operating at full duplex.

E. This is a port on a network interface card in a PC.

Explanation/Reference:
Modern Ethernet networks built with switches and full-duplex connections no longer utilize CSMA/CD. CSMA/CD is only used in obsolete shared media Ethernet (which uses repeater or hub).

3. A receiving host computes the checksum on a frame and determines that the frame is damaged. The frame is then discarded. At which OSI layer did this happen?

A. session

B. transport

C. network

D. data link

E. physical

Explanation/Reference:
The Data Link layer provides the physical transmission of the data and handles error notification, network topology, and flow control. The Data Link layer formats the message into pieces, each called a data frame,and adds a customized header containing the hardware destination and source address. Protocols Data Unit (PDU) on Datalink layer is called frame. According to this question the frame is damaged and discarded which will happen at the Data Link layer.

4. Which of the following correctly describe steps in the OSI data encapsulation process? (Choose two.)

A. The transport layer divides a data stream into segments and may add reliability and flow control information

B. The data link layer adds physical source and destination addresses and an FCS to the segment.

C. Packets are created when the network layer encapsulates a frame with source and destination host

addresses and protocol-related control information.

D. Packets are created when the network layer adds Layer 3 addresses and control information to a segment.

E. The presentation layer translates bits into voltages for transmission across the physical link.

Explanation/Reference:
The Application Layer (Layer 7) refers to communications services to applications and is the interface between the network and the application. Examples include. Telnet, HTTP, FTP, Internet browsers, NFS, SMTP gateways, SNMP, X.400 mail, and FTAM. The Presentation Layer (Layer 6) defining data formats, such as ASCII text, EBCDIC text, binary, BCD, and JPEG. Encryption also is defined as a presentation layer service. Examples include. JPEG, ASCII, EBCDIC, TIFF, GIF, PICT, encryption, MPEG, and MIDI.
The Session Layer (Layer 5) defines how to start, control, and end communication sessions. This includes the control and management of multiple bidirectional messages so that the application can be notified if only some of a series of messages are completed. This allows the presentation layer to have a seamless view of an incoming stream of data. The presentation layer can be presented with data if all flows occur in some cases. Examples include. RPC, SQL, NFS, NetBios names, AppleTalk ASP, and DECnet SCP The Transport Layer (Layer 4) defines several functions, including the choice of protocols.

The most important Layer 4 functions are error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols.

Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. Examples include. TCP, UDP, and SPX. The Network Layer (Layer 3) defines end-to-end delivery of packets and defines logical addressing to accomplish this. It also defines how routing works and how routes are learned; and how to fragment a packet into smaller packets to accommodate media with smaller maximum transmission unit sizes.

Examples include. IP, IPX, AppleTalk DDP, and ICMP. Both IP and IPX define logical addressing, routing, the learning of routing information, and end-to-end delivery rules. The IP and IPX protocols most closely match the OSI network layer (Layer 3) and are called Layer 3 protocols because their functions most closely match OSI’s Layer 3. The Data Link Layer (Layer 2) is concerned with getting data across one particular link or medium.

The data link protocols define delivery across an individual link. These protocols are necessarily concerned with the type of media in use. Examples includE. IEEE 802.3/802.2, HDLC, Frame Relay, PPP, FDDI, ATM, and IEEE 802.5/802.2.

5. Refer to the graphic. Host A is communicating with the server. What will be the source MAC address of the
frames received by Host A from the server?

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A. the MAC address of router interface e0

B. the MAC address of router interface e1

C. the MAC address of the server network interface

D. the MAC address of host A

Explanation/Reference:
Whereas switches can only examine and forward packets based on the contents of the MAC header, routers can look further into the packet to discover the network for which a packet is destined. Routers make forwarding decisions based on the packet’s network-layer header (such as an IPX header or IP header). These network-layer headers contain source and destination network addresses. Local devices address packets to the router’s MAC address in the MAC header. After receiving the packets, the router must perform the following steps:
Check the incoming packet for corruption, and remove the MAC header . The router checks the packet for MAC-layer errors. The router then strips off the MAC header and examines the network- layer header to determine what to do with the packet.
Examine the age of the packet. The router must ensure that the packet has not come too far to be forwarded. For example, IPX headers contain a hop count. By default, 15 hops is the maximum number of hops (or routers) that a packet can cross. If a packet has a hop count of 15, the router discards the packet.
IP headers contain a Time to Live (TTL) value. Unlike the IPX hop count, which increments as the packet is forwarded through each router, the IP TTL value decrements as the IP packet is forwarded through each router. If an IP packet has a TTL value of 1, the router discards the packet. A router cannot decrement the TTL value to 1 and then forward the packet. Determine the route to the destination. Routers maintain a routing table that lists available networks, the direction to the desired network (the outgoing interface number), and the distance to those networks. After determining which direction to forward the packet, the router must build a new header. (If you want to read the IP routing tables on a Windows 95/98 workstation, type
ROUTE PRINT in the DOS box.)
Build the new MAC header and forward the packet. Finally, the router builds a new MAC header for the packet. The MAC header includes the router’s MAC address and the final destination’s MAC address or the MAC address of the next router in the path.

6. Refer to the exhibit. What two results would occur if the hub were to be replaced with a switch that is configured with one Ethernet VLAN? (Choose two.)

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A. The number of collision domains would remain the same.
B. The number of collision domains would decrease.
C. The number of collision domains would increase.
D. The number of broadcast domains would remain the same.
E. The number of broadcast domains would decrease.
F. The number of broadcast domains would increase.

Explanation/Reference:
Basically, a collision domain is a network segment that allows normal network traffic to flow back and forth. In the old days of hubs, this meant you had a lot of collisions, and the old CSMA/CD would be working overtime to try to get those packets re-sent every time there was a collision on the wire (since ethernet allows only one host to be transmitting at once without there being a traffic jam). With switches, you break up collision domains by switching packets bound for other collision domains. These days, since we mostly use switches to connect computers to the network, you generally have one collision domain to a PC.

Broadcast domains are exactly what they imply: they are network segments that allow broadcasts to be sent across them. Since switches and bridges allow for broadcast traffic to go unswitched, broadcasts can traverse collision domains freely. Routers, however, don’t allow broadcasts through by default, so when a broadcast hits a router (or the perimeter of a VLAN), it doesn’t get forwarded. The simple way to look at it is this way: switches break up collision domains, while routers (and VLANs) break up collision domains and broadcast domains. Also, a broadcast domain can contain multiple collision domains, but a collision domain can never have more than one broadcast domain associated with it.

Collision Domain: A group of Ethernet or Fast Ethernet devices in a CSMA/CD LAN that are connected by repeaters and compete for access on the network. Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network in order to avoid data collisions. A collision domain is sometimes referred to as an Ethernet segment.

Broadcast Domain: Broadcasting sends a message to everyone on the local network (subnet). An example for Broadcasting would be DHCP Request from a Client PC. The Client is asking for a IP Address, but the client does not know how to reach the DHCP Server. So the client sends a DHCP Discover packet to EVERY PC in the local subnet (Broadcast). But only the DHCP Server will answer to the Request.

How to count them?

Broadcast Domain:

No matter how many hosts or devices are connected together, if they are connected with a repeater, hub, switch or bridge, all these devices are in ONE Broadcast domain (assuming a single VLAN). A Router is used to separate Broadcast-Domains (we could also call them Subnets – or call them VLANs). So, if a router stands between all these devices, we have TWO broadcast domains.

Collision Domain:
Each connection from a single PC to a Layer 2 switch is ONE Collision domain. For example, if 5 PCs are connected with separate cables to a switch, we have 5 Collision domains. If this switch is connected to another switch or a router, we have one collision domain more. If 5 Devices are connected to a Hub, this is ONE Collision Domain. Each device that is connected to a Layer 1 device (repeater, hub) will reside in ONE single collision domain.

7. Which three statements accurately describe Layer 2 Ethernet switches? (Choose three.)

A. Spanning Tree Protocol allows switches to automatically share VLAN information.

B. Establishing VLANs increases the number of broadcast domains.

C. Switches that are configured with VLANs make forwarding decisions based on both Layer 2 and Layer 3 address information.

D. Microsegmentation decreases the number of collisions on the network.

E. In a properly functioning network with redundant switched paths, each switched segment will contain  one root bridge with all its ports in the forwarding state. All other switches in that broadcast domain will  have only one root port.

F. If a switch receives a frame for an unknown destination, it uses ARP to resolve the address.

Explanation/Reference:
Microsegmentation is a network design (functionality) where each workstation or device on a network gets its own dedicated segment (collision domain) to the switch. Each network device gets the full bandwidth of the segment and does not have to share the segment with other devices. Microsegmentation reduces and can even eliminate collisions because each segment is its own collision domain -> .

Note: Microsegmentation decreases the number of collisions but it increases the number of collision
domains.
8. Where does routing occur within the DoD TCP/IP reference model?

A. application
B. internet
C. network
D. transport

Explanation/Reference:
The picture below shows the comparison between TCP/IP model & OSI model. Notice that the Internet Layer of TCP/IP is equivalent to the Network Layer which is responsible for routing decision.

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9. Refer to exhibit: Which destination addresses will be used by Host A to send data to Host C? (Choose two.)

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A. the IP address of Switch 1
B. the MAC address of Switch 1
C. the IP address of Host C
D. the MAC address of Host C
E. the IP address of the router’s E0 interface
F. the MAC address of the router’s E0 interface

Explanation/Reference:
While transferring data through many different networks, the source and destination IP addresses are not changed. Only the source and destination MAC addresses are changed. So in this case Host A will use the IP address of Host C and the MAC address of E0 interface to send data.
When the router receives this data, it replaces the source MAC address with it own E1 interface’s  MAC address and replaces the destination MAC address with Host C’s MAC address before sending to Host C .

10. Refer to the exhibit. What will Router1 do when it receives the data frame shown? (Choose three.)

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A. Router1 will strip off the source MAC address and replace it with the MAC address 0000.0c36.6965.

B. Router1 will strip off the source IP address and replace it with the IP address 192.168.40.1.

C. Router1 will strip off the destination MAC address and replace it with the MAC address 0000.0c07.4320.

D. Router1 will strip off the destination IP address and replace it with the IP address of 192.168.40.1.

E. Router1 will forward the data packet out interface FastEthernet0/1.

F. Router1 will forward the data packet out interface FastEthernet0/2

11. Refer to the exhibit. Which three statements correctly describe Network Device A? (Choose three.)

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A. With a network wide mask of 255.255.255.128, each interface does not require an IP address.

B. With a network wide mask of 255.255.255.128, each interface does require an IP address on a unique IP subnet.

C. With a network wide mask of 255.255.255.0, must be a Layer 2 device for the PCs to communicate with each other.

D. With a network wide mask of 255.255.255.0, must be a Layer 3 device for the PCs to communicate  with each other.

E. With a network wide mask of 255.255.254.0, each interface does not require an IP address.

12 .Which layer in the OSI reference model is responsible for determining the availability of the receiving program and checking to see if enough resources exist for that communication?

A. transport

B. network

C. presentation

D. session

E. application

13. Refer to the exhibit. Host A pings interface S0/0 on router 3. What is the TTL value for that ping?

3sdfc

A. 252

B. 253

C. 254

D. 255

Explanation/Reference:
From the CCNA ICND2 Exam book: “Routers decrement the TTL by 1 every time they forward a packet; if a router decrements the TTL to 0, it throws away the packet. This prevents packets from rotating forever.” I want to make it clear that before the router forwards a packet, the TTL is still remain the same. For example in the topology above, pings to S0/1 and S0/0 of Router 2 have the same TTL.

14. Which of the following describes the roles of devices in a WAN? (Choose three.)

A. A CSU/DSU terminates a digital local loop.

B. A modem terminates a digital local loop.

C. A CSU/DSU terminates an analog local loop.

D. A modem terminates an analog local loop.

E. A router is commonly considered a DTE device.

F. A router is commonly considered a DCE device.

15. Refer to the exhibit. Refer to the exhibit. After HostA pings HostB, which entry will be in the ARP cache of HostA to support this transmission?

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A. (Correct Answer: A)5

B. 5

C. 5-c

D. 5-d

Explanation/Reference:
A Explanation:
When a host needs to reach a device on another subnet, the ARP cache entry will be that of the Ethernet address of the local router (default gateway) for the physical MAC address. The destination IP address will not change, and will be that of the remote host (HostB).

16. For what two purposes does the Ethernet protocol use physical addresses? (Choose two.)

A. to uniquely identify devices at Layer 2
B. to allow communication with devices on a different network
C. to differentiate a Layer 2 frame from a Layer 3 packet
D. to establish a priority system to determine which device gets to transmit first
E. to allow communication between different devices on the same network
F. to allow detection of a remote device when its physical address is unknown

Explanation/Reference:
Physical addresses or MAC addresses are used to identify devices at layer 2.  MAC addresses are only used to communicate on the same network. To communicate on different networkwe have to use Layer 3 addresses (IP addresses) -> B is not correct. Layer 2 frame and Layer 3 packet can be recognized via headers. Layer 3 packet also contains physical address ->
On Ethernet, each frame has the same priority to transmit by default -> All devices need a physical address to identify itself. If not, they can not communicate ->

17. Refer to the exhibit. Based on the information given, which switch will be elected root bridge and why?

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A. Switch A, because it has the lowest MAC address
B. Switch A, because it is the most centrally located switch
C. Switch B, because it has the highest MAC address
D. Switch C, because it is the most centrally located switch
E. Switch C, because it has the lowest priority
F. Switch D, because it has the highest priority

Explanation/Reference:
To elect the root bridge in the LAN, first check the priority value. The switch having the lowest priority will win the election process. If Priority Value is the same then it checks the MAC Address; the switch having the lowest MAC Address will become the root bridge. In this case, switch C has the lowest MAC Address so it becomes the root bridge.

18. Refer to the exhibit. Switch-1 needs to send data to a host with a MAC address of 00b0.d056.efa4. What will Switch-1 do with this data?

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A. Switch-1 will drop the data because it does not have an entry for that MAC address.
B. Switch-1 will flood the data out all of its ports except the port from which the data originated. C. Switch-1 will send an ARP request out all its ports except the port from which the data originated.
D. Switch-1 will forward the data to its default gateway.

Explanation/Reference:
This question tests the operating principles of the Layer 2 switch. Check the MAC address table of Switch1 and find that the MAC address of the host does not exist in the table. Switch1 will flood the data out all of its ports except the port from which the data originated to determine which port the host is located in. Switches work as follows: In output there is no MAC address of give host so switch floods to all ports except the source port.

19. What value is primarily used to determine which port becomes the root port on each nonroot switch in a spanning-tree topology?

A. path cost
B. lowest port MAC address
C. VTP revision number
D. highest port priority number
E. port priority number and MAC address

Explanation/Reference:
The path cost to the root bridge is the most important value to determine which port will become the root port on each non-root switch. In particular, the port with lowest cost to the root bridge will become root port (on non-root switch).

20. What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?

A. It creates a VLAN 999 interface
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.

Explanation/Reference:
Configuring the Native VLAN for Untagged Traffic  A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default, the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is VLAN 1 by default.

21. Which two protocols are used by bridges and/or switches to prevent loops in a layer 2 network?  (Choose two.)

A. 802.1d
B. VTP
C. 802.1q
D. STP
E. SAP

Explanation/Reference:
This question is to examine the STP protocol.
STP (802.1d) is used to prevent Layer 2 loops.
802.1q is a Frame Relay protocol which belongs to VLAN.
SAP is a concept of the OSI model.

22. Which switch would STP choose to become the root bridge in the selection process?

A. 32768: 11-22-33-44-55-66
B. 32768: 22-33-44-55-66-77
C. 32769: 11-22-33-44-55-65
D. . 32769: 22-33-44-55-66-78

23. A switch is configured with all ports assigned to vlan 2 with full duplex FastEthernet to segment existing departmental traffic. What is the effect of adding switch ports to a new VLAN on the switch?

A. More collision domains will be created.
B. IP address utilization will be more efficient.
C. More bandwidth will be required than was needed previously.
D. An additional broadcast domain will be created.

Explanation/Reference:
Each VLAN creates its own broadcast domain. Since this is a full duplex switch, each port is a separate collision domain.

24. What are three benefits of implementing VLANs? (Choose three.)

A. A higher level of network security can be reached by separating sensitive data traffic from other network traffic.

B. A more efficient use of bandwidth can be achieved allowing many physical groups to use the same
network infrastructure.

C. A more efficient use of bandwidth can be achieved allowing many logical networks to use the same  network infrastructure.

D. Broadcast storms can be mitigated by increasing the number of broadcast domains, thus reducing their size.

E. Broadcast storms can be mitigated by decreasing the number of broadcast domains, thus increasing
their size.

F. VLANs make it easier for IT staff to configure new logical groups, because the VLANs all belong to the same broadcast domain.

G. Port-based VLANs increase switch-port use efficiency, thanks to 802.1Q trunks.

Explanation/Reference:
Benefits of VLANs
VLAN is a network structure which allows users to communicate while in different locations by sharing one multicast domain and a single broadcast. They provide numerous networking benefits and have become popular in the market. For instance, it helps reduce administrative costs when users are geographically
dispersed.

1. Inexpensive
The popularity of VLANs is due to the fact that changes, adds, and moves can be attained simply by making necessary configurations on the VLAN port. Time-consuming, re-addressing, and host reconfigurations is now a thing of the past, because network configuration can be made at ease when need arises.

2. Better management
A VLAN typically solve the scalability issues that exist in a large network by breaking the main domain into several VLAN groups or smaller broadcast configurations, thereby encourage better control of multicast traffic as well as broadcast domains. Improves network security High-security can be positioned in different VLAN groups to ensure that non-members cannot receive their broadcasts. On the other hand, a router is added and workgroups relocated into centralized locations.
Enhances performance  A more efficient use of bandwidth can be achieved allowing many logical networks to use the same network infrastructure.

5. Segment multiple networks
VLANs are typically used to achieve multiple purposes. They are popularly used to reduce broadcast traffic. Each VLAN creates a separate, smaller broadcast domain.

6. Better administration
VLANs facilitate grouping of multiple geographical stations. When VLAN users move to another physical
location, the network does not have to be configured.

25. Which IEEE standard protocol is initiated as a result of successful DTP completion in a switch over Fast Ethernet?

A. 802.3ad
B. 802.1w
C. 802.1D
D. 802.1Q

Explanation/Reference:
Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol for negotiating trunking on a link between two devices and for negotiating the type of trunking encapsulation (802.1Q) to be used.

26. Which of the following are benefits of VLANs? (Choose three.)

A. They increase the size of collision domains.

B. They allow logical grouping of users by function.

C. They can enhance network security.

D. They increase the size of broadcast domains while decreasing the number of collision domains.

E. They increase the number of broadcast domains while decreasing the size of the broadcast domains.

F. They simplify switch administration.

Explanation/Reference:
When using VLAN the number and size of collision domains remain the same -> VLANs allow to group users by function, not by location or geography -> . VLANs help minimize the incorrect configuration of VLANs so it enhances the security of the network -> . VLAN increases the size of broadcast domains but does not decrease the number of collision domains ->
VLANs increase the number of broadcast domains while decreasing the size of the broadcast domains which increase the utilization of the links. It is also a big advantage of VLAN -> . VLANs are useful but they are more complex and need more administration ->

27. Refer to the exhibit. A technician has installed SwitchB and needs to configure it for remote access from the management workstation connected to SwitchA . Which set of commands is required to accomplish this task?

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A. SwitchB(config)# interface FastEthernet 0/1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# no shutdown

B. B. SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# ip default-gateway 192.168.8.254 255.255.255.0 SwitchB
(config-if)# no shutdown

C. SwitchB(config)# ip default-gateway 192.168.8.254
SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0 SwitchB(config-
if)# no shutdown

D. SwitchB(config)# ip default-network 192.168.8.254
SwitchB(config)# interface vlan 1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0 SwitchB(config-
if)# no shutdown

E. SwitchB(config)# ip route 192.168.8.254 255.255.255.0
SwitchB(config)# interface FastEthernet 0/1
SwitchB(config-if)# ip address 192.168.8.252 255.255.255.0
SwitchB(config-if)# no shutdown

Explanation/Reference:
To remote access to SwitchB, it must have a management IP address on a VLAN on that switch. Traditionally, we often use VLAN 1 as the management VLAN (but in fact it is not secure). In the exhibit, we can recognize that the Management Workstation is in a different subnet from the SwitchB. For intersubnetwork communication to occur, you must configure at least one default gateway. This default gateway is used to forward traffic originating from the switch only, not to forward traffic sent by devices connected to the switch.

28. In an Ethernet network, under what two scenarios can devices transmit? (Choose two.)

A. when they receive a special token
B. when there is a carrier
C. when they detect no other devices are sending
D. when the medium is idle
E. when the server grants access

Explanation/Reference:
Ethernet network is a shared environment so all devices have the right to access to the medium. If more than one device transmits simultaneously, the signals collide and can not reach the destination.  If a device detects another device is sending, it will wait for a specified amount of time before attempting to transmit.
When there is no traffic detected, a device will transmit its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.

29. Which two states are the port states when RSTP has converged? (Choose two.)

A. discarding
B. listening
C. learning
D. forwarding
E. disabled

30. Which two commands can be used to verify a trunk link configuration status on a given Cisco switch interface? (Choose two.)

A. show interface trunk
B. show interface interface
C. show ip interface brief
D. show interface vlan
E. show interface switchport

31. Which of the following statements describe the network shown in the graphic? (Choose two.)

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A. There are two broadcast domains in the network.
B. There are four broadcast domains in the network.
C. There are six broadcast domains in the network
D. There are four collision domains in the network.
E. There are five collision domains in the network.
F. There are seven collision domains in the network.

Explanation/Reference:
Explanation:
Only router can break up broadcast domains so in the exhibit there are 2 broadcast domains: from e0 interface to the left is a broadcast domain and from e1 interface to the right is another broadcast domain ->.
Both router and switch can break up collision domains so there is only 1 collision domain on the left of the router (because hub doesn’t break up collision domain) and there are 6 collision domains on the right of the router (1 collision domain from e1 interface to the switch + 5 collision domains for 5 PCs in Production) ->

32. Which command enables RSTP on a switch?

A. spanning-tree uplinkfast
B. spanning-tree mode rapid-pvst
C. spanning-tree backbonefast
D. spanning-tree mode mst

Explanation/Reference:
Ethernet network is a shared environment so all devices have the right to access to the medium. If more than one device transmits simultaneously, the signals collide and can not reach the destination.  If a device detects another device is sending, it will wait for a specified amount of time before attempting to transmit.
When there is no traffic detected, a device will transmit its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.

33. Refer to the exhibit. All switch ports are assigned to the correct VLANs, but none of the hosts connected to SwitchA can communicate with hosts in the same VLAN connected to SwitchB. Based on the output shown, what is the most likely problem?

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A. The access link needs to be configured in multiple VLANs.
B. The link between the switches is configured in the wrong VLAN.
C. The link between the switches needs to be configured as a trunk.
D. VTP is not configured to carry VLAN information between the switches.
E. Switch IP addresses must be configured in order for traffic to be forwarded between the switches.

Explanation/Reference:
In order to pass traffic from VLANs on different switches, the connections between the switches must be configured as trunk ports.

34. What is the function of the command switchport trunk native vlan 999 on a Cisco Catalyst switch?

A. It creates a VLAN 999 interface.
B. It designates VLAN 999 for untagged traffic.
C. It blocks VLAN 999 traffic from passing on the trunk.
D. It designates VLAN 999 as the default for all unknown tagged traffic.

Explanation/Reference:
Configuring the Native VLAN for Untagged Traffic A trunk port configured with 802.1Q tagging can receive both tagged and untagged traffic. By default, the switch forwards untagged traffic in the native VLAN configured for the port. The native VLAN is VLAN 1 by default.

35. Refer to the exhibit. Given the output shown from this Cisco Catalyst 2950, what is the reason that interface FastEthernet 0/10 is not the root port for VLAN 2?

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A. This switch has more than one interface connected to the root network segment in VLAN 2.
B. This switch is running RSTP while the elected designated switch is running 802.1d Spanning Tree.
C. This switch interface has a higher path cost to the root bridge than another in the topology.
D. This switch has a lower bridge ID for VLAN 2 than the elected designated switch.

Explanation/Reference:
Since the port is in the blocked status, we must assume that there is a shorter path to the root bridge
elsewhere.

36. Why will a switch never learn a broadcast address?

A. Broadcasts only use network layer addressing.
B. A broadcast frame is never forwarded by a switch.
C. A broadcast address will never be the source address of a frame.
D. Broadcast addresses use an incorrect format for the switching table.
E. Broadcast frames are never sent to switches.

Explanation/Reference:
Switches dynamically learn MAC addresses based on the source MAC addresses that it sees, and since a broadcast is never the source, it will never learn the broadcast address.

37. Refer to the exhibit. Why has this switch not been elected the root bridge for VLAN1?

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A. It has more than one interface that is connected to the root network segment.
B. It is running RSTP while the elected root bridge is running 802.1d spanning tree
C. It has a higher MAC address than the elected root bridge.
D. It has a higher bridge ID than the elected root bridge.

Explanation/Reference:
The root bridge is determined by the lowest bridge ID, and this switch has a bridge ID priority of 32768, which is higher than the roots priority of 20481.

38. Which two link protocols are used to carry multiple VLANs over a single link? (Choose two.)

A. VTP
B. 802.1q
C. IGP
D. ISL
E. 802.3u

Explanation/Reference:
Cisco switches can use two different encapsulation types for trunks, the industry standard 802.1q or the Cisco proprietary ISL. Generally, most network engineers prefer to use 802.1q since it is standards based and will interoperate with other vendors.

39. Assuming the default switch configuration, which VLAN range can be added, modified, and removed on a Cisco switch?

A. 1 through 1001
B. 2 through 1001
C. 1 through 1002
D. 2 through 1005

Explanation/Reference:
VLAN 1 is the default VLAN on Cisco switch. It always exists and can not be added, modified or removed.
VLANs 1002-1005 are default VLANs for FDDI & Token Ring and they can’t be deleted or used for
Ethernet.

40. Which statement about VLAN operation on Cisco Catalyst switches is true?

A. When a packet is received from an 802.1Q trunk, the VLAN ID can be determined from the source
MAC address and the MAC address table.
B. Unknown unicast frames are retransmitted only to the ports that belong to the same VLAN.
C. Broadcast and multicast frames are retransmitted to ports that are configured on different VLAN.
D. Ports between switches should be configured in access mode so that VLANs can span across the
ports.

41. Refer to the topology shown in the exhibit. Which ports will be STP designated ports if all the links ar operating at the same bandwidth? (Choose three.)

17

A. Switch A – Fa0/0
B. Switch A – Fa0/1
C. Switch B – Fa0/0
D. Switch B – Fa0/1
E. Switch C – Fa0/0
F. Switch C – Fa0/1

Explanation/Reference:
This question is to check the spanning tree election problem. First, select the root bridge, which can be accomplished by comparing the bridge ID, the smallest will be selected. Bridge-id= bridge priority + MAC address. The three switches in the figure all have the default priority, so we should compare the MAC address, it is easy to find that SwitchB is the root bridge.
Select the root port on the non-root bridge, which can be completed through comparing root path cost. The smallest will be selected as the root port.
Next, select the Designated Port. First, compare the path cost, if the costs happen to be the same, then compare the BID, still the smallest will be selected. Each link has a DP. Based on the exhibit above, we can find DP on each link. The DP on the link between SwitchA and SwitchC is SwitchA’Fa0/1, because it has the smallest MAC address.

42. Refer to the exhibit. How should the FastEthernet0/1 ports on the 2950 model switches that are shown in the exhibit be configured to allow connectivity between all devices?

18

A. The ports only need to be connected by a crossover cable.

B. SwitchX(config)# interface fastethernet 0/1
SwitchX(config-if)# switchport mode trunk

C.SwitchX (config)# interface fastethernet 0/1
SwitchX (config-if)# switchport mode trunk

D.SwitchX(config)# interface fastethernet 0/1
SwitchX(config-if)# switchport mode trunk

43. Which three statements about RSTP are true? (Choose three.)

A. RSTP significantly reduces topology reconverging time after a link failure.
B. RSTP expands the STP port roles by adding the alternate and backup roles
C. RSTP port states are blocking, discarding, learning, or forwarding.
D. RSTP provides a faster transition to the forwarding state on point-to-point links than STP does.
E. RSTP also uses the STP proposal-agreement sequence.
F. RSTP uses the same timer-based process as STP on point-to-point links.

Explanation/Reference:
One big disadvantage of STP is the low convergence which is very important in switched network. To overcome this problem, in 2001, the IEEE with document 802.1w introduced an evolution of the Spanning Tree Protocol: Rapid Spanning Tree Protocol (RSTP), which significantly reduces the convergence time after a topology change occurs in the network. While STP can take 30 to 50 seconds to transit from a blocking state to a forwarding state, RSTP is typically able to respond less than 10 seconds of a physical link failure.

RSTP works by adding an alternative port and a backup port compared to STP. These ports are allowed to immediately enter the forwarding state rather than passively wait for the network to converge.  RSTP bridge port roles: Root port – A forwarding port that is the closest to the root bridge in terms of path cost  Designated port – A forwarding port for every LAN segment
Alternate port – A best alternate path to the root bridge. This path is different than using the root port. The alternative port moves to the forwarding state if there is a failure on the designated port for the segment.

Backup port – A backup/redundant path to a segment where another bridge port already connects. The backup port applies only when a single switch has two links to the same segment (collision domain). To have two links to the same collision domain, the switch must be attached to a hub. Disabled port – Not strictly part of STP, a network administrator can manually disable a port

44. Refer to the exhibit. A frame on VLAN 1 on switch S1 is sent to switch S2 where the frame is received on VLAN 2. What causes this behavior?

19

A. trunk mode mismatches
B. allowing only VLAN 2 on the destination
C. native VLAN mismatches
D. VLANs that do not correspond to a unique IP subnet

Explanation/Reference:
Untagged frames are encapsulated with the native VLAN. In this case, the native VLANs are different so although S1 will tag it as VLAN 1 it will be received by S2.

45. At which layer of the OSI model is RSTP used to prevent loops?

A. physical
B. data link
C. network
D. transport

Explanation/Reference:
RSTP and STP operate on switches and are based on the exchange of Bridge Protocol Data Units (BPDUs) between switches. One of the most important fields in BPDUs is the Bridge Priority in which the MAC address is used to elect the Root Bridge -> RSTP operates at Layer 2 ?Data Link layer -> .

46. What does a Layer 2 switch use to decide where to forward a received frame?

A. source MAC address
B. source IP address C. source switch port
C. destination IP address
D. destination port address
E. source switch port
F. destination MAC address

Explanation/Reference:
When a frame is received, the switch looks at the destination hardware address and finds the interface if it is in its MAC address table. If the address is unknown, the frame is broadcast on all interfaces except the one it was received on.

47. Refer to the exhibit. Which statement is true?

20

A. The Fa0/11 role confirms that SwitchA is the root bridge for VLAN 20.
B. VLAN 20 is running the Per VLAN Spanning Tree Protocol.
C. The MAC address of the root bridge is 0017.596d.1580.
D. SwitchA is not the root bridge, because not all of the interface roles are designated.

Explanation/Reference:
Only non-root bridge can have root port. Fa0/11 is the root port so we can confirm this switch is not the root bridge ->
From the output we learn this switch is running Rapid STP, not PVST -> 0017.596d.1580 is the MAC address of this switch, not of the root bridge. The MAC address of the root bridge is 0017.596d.2a00 ->  All of the interface roles of the root bridge are designated. SwitchA has one Root port and 1 Alternative port so it is not the root bridge.

48. Which two benefits are provided by creating VLANs? (Choose two.)

A. added security
B. dedicated bandwidth
C. provides segmentation
D. allows switches to route traffic between subinterfaces
E. contains collisions

Explanation/Reference:
A VLAN is a switched network that is logically segmented on an organizational basis, by functions, project teams, or applications rather than on a physical or geographical basis. Security: VLANs also improve security by isolating groups. High-security users can be grouped into a VLAN, possible on the same physical segment, and no users outside that VLAN can communicate with them LAN Segmentation VLANs allow logical network topologies to overlay the physical switched infrastructure such that any arbitrary collection of LAN ports can be combined into an autonomous user group or community of interest. The technology logically segments the network into separate Layer 2 broadcast domains whereby packets
are switched between ports designated to be within the same VLAN. By containing traffic originating on a particular LAN only to other LANs in the same VLAN, switched virtual networks avoid wasting bandwidth.

49. Which command can be used from a PC to verify the connectivity between hosts that connect through a switch in the same LAN?

A. pingaddress
B. tracert address
C. traceroute address
D. arpaddress

Explanation/Reference:
ICMP pings are used to verify connectivity between two IP hosts. Traceroute is used to verify the router hop path traffic will take but in this case since the hosts are in the same LAN there will be no router hops involved.

50. Based on the network shown in the graphic. Which option contains both the potential networking problem and the protocol or setting that should be used to prevent the problem?

21

A. routing loops, hold down timers
B. switching loops, split horizon
C. routing loops, split horizon
D. switching loops, VTP
E. routing loops, STP
F. switching loops, STP

Explanation/Reference:
The Spanning-Tree Protocol (STP) prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.

51. Refer to the exhibit. Which two statements are true about interVLAN routing in the topology that is shown in the exhibit? (Choose two.)

22

A. Host E and host F use the same IP gateway address.

B. Router1 and Switch2 should be connected via a crossover cable.

C. Router1 will not play a role in communications between host A and host D

D. The FastEthernet 0/0 interface on Router1 must be configured with subinterfaces.

E. Router1 needs more LAN interfaces to accommodate the VLANs that are shown in the exhibit.

F. The FastEthernet 0/0 interface on Router1 and the FastEthernet 0/1 interface on Switch2 trunk ports must be configured using the same encapsulation type

52. Which two of these are characteristics of the 802.1Q protocol? (Choose two.)

A. It is used exclusively for tagging VLAN frames and does not address network reconvergence
B. It modifies the 802.3 frame header, and thus requires that the FCS be recomputed.
C. It is a Layer 2 messaging protocol which maintains VLAN configurations across networks.
D. It includes an 8-bit field which specifies the priority of a frame.
E. It is a trunking protocol capable of carrying untagged frames.

Explanation/Reference:
802.1Q protocol, or Virtual Bridged Local Area Networks protocol, mainly stipulates the realization of the VLAN. 802.1Q is a standardized relay method that inserts 4 bytes field into the original Ethernet frame and re-calculate the FCS. 802.1Q frame relay supports two types of frame: marked and non-marked. Non- marked frame carries no VLAN identification information.

53. Refer to the exhibit. Each of these four switches has been configured with a hostname, as well as being configured to run RSTP. No other configuration changes have been made. Which three of these show the correct RSTP port roles for the indicated switches and interfaces? (Choose three.)

23

A. SwitchA, Fa0/2, designated
B. SwitchA, Fa0/1, root
C. SwitchB, Gi0/2, root
D. SwitchB, Gi0/1, designated
E. SwitchC, Fa0/2, root
F. SwitchD, Gi0/2, root

Explanation/Reference:
The question says “no other configuration changes have been made” so we can understand these switches have the same bridge priority. Switch C has lowest MAC address so it will become root bridge and 2 of its ports (Fa0/1 & Fa0/2) will be designated ports. Because SwitchC is the root bridge so the 2 ports nearest SwitchC on SwitchA (Fa0/1) and SwitchD (Gi0/2) will be root ports..
Now we come to the most difficult part of this question: SwitchB must have a root port so which port will it choose? To answer this question we need to know about STP cost and port cost. In general, “cost” is calculated based on bandwidth of the link. The higher the bandwidth on a link, the lower the value of its cost. Below are the cost values you should memorize:

24

SwitchB will choose the interface with lower cost to the root bridge as the root port so we must calculate the cost on interface Gi0/1 & Gi0/2 of SwitchB to the root bridge. This can be calculated from the “cost to the root bridge” of each switch because a switch always advertises its cost to the root bridge in its BPDU. The receiving switch will add its local port cost value to the cost in the BPDU. One more thing to notice is that a root bridge always advertises the cost to the root bridge (itself) with an initial value of 0. Now let’s have a look at the topology again

25

SwitchC advertises its cost to the root bridge with a value of 0. Switch D adds 4 (the cost value of 1Gbps link) and advertises this value (4) to SwitchB. SwitchB adds another 4 and learns that it can reach SwitchC via Gi0/1 port with a total cost of 8. The same process happens for SwitchA and SwitchB learns that it canreach SwitchC via Gi0/2 with a total cost of 23 -> Switch B chooses Gi0/1 as its root port ->
Now our last task is to identify the port roles of the ports between SwitchA & SwitchB. It is rather easy as the MAC address of SwitchA is lower than that of SwitchB so Fa0/2 of SwitchA will be designated port while Gi0/2 of SwitchB will be alternative port.

Below summaries all the port roles of these switches:

26

+ DP: Designated Port (forwarding state)
+ RP: Root Port (forwarding state)

54. What is one benefit of PVST+?

A. PVST+ supports Layer 3 load balancing without loops.
B. PVST+ reduces the CPU cycles for all the switches in the network.
C. PVST+ allows the root switch location to be optimized per VLAN.
D. PVST+ automatically selects the root bridge location, to provide optimized bandwidth usage.

Explanation/Reference:
The PVST+ provides Layer 2 load-balancing for the VLAN on which it runs. You can create different logical topologies by using the VLANs on your network to ensure that all of your links are used but that no one link is oversubscribed. Each instance of PVST+ on a VLAN has a single root switch. This root switch propagates the spanning-tree information associated with that VLAN to all other switches in the network.
Because each switch has the same information about the network, this process ensures that the network topology is maintained and optimized per VLAN. http://www.cisco.com/en/US/docs/switches/lan/ catalyst3750x_3560x/software/release/12.2_55_s e/configuration/guide/swstp.html

55. Refer to the exhibit. The network administrator normally establishes a Telnet session with the switch from host A . However, host A is unavailable. The administrator’s attempt to telnet to the switch from host B fails, but pings to the other two hosts are successful. What is the issue?

29

A. Host B and the switch need to be in the same subnet.
B. The switch interface connected to the router is down.
C. Host B needs to be assigned an IP address in VLAN 1.
D. The switch needs an appropriate default gateway assigned.
E. The switch interfaces need the appropriate IP addresses assigned.

Explanation/Reference:
Ping was successful form host B to other hosts because of intervlan routing configured on router. But to manage switch via telnet the VLAN32 on the switch needs to be configured interface vlan32 along with ip address and its appropriate default-gateway address. Since VLAN1 interface is already configure on switch Host A was able to telnet switch.
56. Which are valid modes for a switch port used as a VLAN trunk? (Choose three.)

A. transparent
B. auto
C. on
D. desirable
E. blocking
F. forwarding

57.Refer to the exhibit. Which switch provides the spanning-tree designated port role for the network segment that services the printers?

30

A. SW1
B. SW2
C. SW3
D. SW4

Explanation/Reference:
Printers are connected by hubs. Decide the switch that provides the spanning-tree designated port role between Switch3 and Switch4. They have the same priority 32768. Compare their MAC addresses. Switch3 with a smaller MAC address will provide a designated port for printers.

58. Refer to Exhibit. How many broadcast domains are shown in the graphic assuming only the default VLAN is
configured on the switches?

31

A. 1
B. 2
C. 6
D. 11
Explanation/Reference:
Only router can break up broadcast domains but in this exhibit no router is used so there is only 1 broadcast domain.
For your information, there are 7 collision domains in this exhibit (6 collision domains between hubs & switches + 1 collision between the two switches).

59. Which three of these statements regarding 802.1Q trunking are correct? (Choose three.)

A. 802.1Q native VLAN frames are untagged by default.
B. 802.1Q trunking ports can also be secure ports.
C. 802.1Q trunks can use 10 Mb/s Ethernet interfaces.
D. 802.1Q trunks require full-duplex, point-to-point connectivity.
E. 802.1Q trunks should have native VLANs that are the same at both ends.

Explanation/Reference:
By default, 802.1Q trunk defined Native VLAN in order to forward unmarked frame. Switches can forward Layer 2 frame from Native VLAN on unmarked trunks port. Receiver switches will transmit all unmarked packets to Native VLAN. Native VLAN is the default VLAN configuration of port. Note for the 802.1Q trunk ports between two devices, the same Native VLAN configuration is required on both sides of the link. If the Native VLAN in 802.1Q trunk ports on same trunk link is properly configured, it could lead to layer 2 loops. The 802.1Q trunk link transmits VLAN information through Ethernet.

60. Refer to the exhibit. The output that is shown is generated at a switch. Which three statements are true? (Choose three.)

32

A. All ports will be in a state of discarding, learning, or forwarding.
B. Thirty VLANs have been configured on this switch.
C. The bridge priority is lower than the default value for spanning tree.
D. All interfaces that are shown are on shared media.
E. All designated ports are in a forwarding state. F. This switch must be the root bridge for all VLANs on this switch.

Explanation/Reference:
From the output, we see that all ports are in Designated role (forwarding state). The command “show spanning-tree vlan 30 only shows us information about VLAN 30. We don’t know how many VLAN exists in
this switch ->
The bridge priority of this switch is 24606 which is lower than the default value bridge priority 32768 -> .  All three interfaces on this switch have the connection type “p2p”, which means Point-to-point environment ?not a shared media >;
The only thing we can specify is this switch is the root bridge for VLAN 3o but we can not guarantee it is also the root bridge for other VLANs ->

61. Refer to the exhibit. At the end of an RSTP election process, which access layer switch port will assume the
discarding role?

33

A. Switch3, port fa0/1
B. Switch3, port fa0/12
C. Switch4, port fa0/11
D. Switch4, port fa0/2
E. Switch3, port Gi0/1
F. Switch3, port Gi0/2

Explanation/Reference:
In this question, we only care about the Access Layer switches (Switch3 & 4). Switch 3 has a lower bridge ID than Switch 4 (because the MAC of Switch3 is smaller than that of Switch4) so both ports of Switch3 will be in forwarding state. The alternative port will surely belong to Switch4. Switch4 will need to block one of its ports to avoid a bridging loop between the two switches. But how does Switch4 select its blocked port?
Well, the answer is based on the BPDUs it receives from Switch3. A BPDU is superior than another if it has:
A lower Root Bridge ID
A lower path cost to the Root
A lower Sending Bridge ID
A lower Sending Port ID
These four parameters are examined in order. In this specific case, all the BPDUs sent by  Switch3 have the same Root Bridge ID, the same path cost to the Root and the same Sending Bridge ID.The only parameter left to select the best one is the Sending Port ID (Port ID = port priority + port index). In this case the port priorities are equal because they use the default value, so Switch4 will compare port index values, which are unique to each port on the switch, and because Fa0/12 is inferior to Fa0/1, Switch4 will select the port connected with Fa0/1 (of Switch3) as its root port and block the other port -> Port fa0/11 of Switch4 will be blocked (discarding role).

62. Which term describes a spanning-tree network that has all switch ports in either the blocking or fowarding
state?

A. converged
B. redundant
C. provisioned
D. spanned

Explanation/Reference:
Spanning Tree Protocol convergence (Layer 2 convergence) happens when bridges and switches have transitioned to either the forwarding or blocking state. When layer 2 is converged, root bridge is elected and all port roles (Root, Designated and Non-Designated) in all switches are selected.

63. What are the possible trunking modes for a switch port? (Choose three.)

A. transparent
B. auto
C. on
D. desirable
E. client
F. forwarding

64. Which two of these statements regarding RSTP are correct? (Choose two.)

A. RSTP cannot operate with PVST+.
B. RSTP defines new port roles.
C. RSTP defines no new port states.
D. RSTP is a proprietary implementation of IEEE 802.1D STP.
E. RSTP is compatible with the original IEEE 802.1D STP.

Explanation/Reference:
When network topology changes, rapid spanning tree protocol (IEEE802.1W, referred to as RSTP) will speed up significantly the speed to re-calculate spanning tree. RSTP not only defines the role of other ports: alternative port and backup port, but also defines status of 3 ports: discarding status, learning status,forwarding status.  RSTP is 802.1D standard evolution, not revolution. It retains most of the parameters, and makes no changes.

65. Refer to the exhibit. Which two statements are true of the interfaces on Switch1? (Choose two.)

34

A. Multiple devices are connected directly to FastEthernet0/1.
B. A hub is connected directly to FastEthernet0/5.
C. FastEthernet0/1 is connected to a host with multiple network interface cards.
D. FastEthernet0/5 has statically assigned MAC addresses.
E. FastEthernet0/1 is configured as a trunk link.
F. Interface FastEthernet0/2 has been disabled.

Explanation/Reference:
Carefully observe the information given after command show. Fa0/1 is connected to Switch2, seven MAC addresses correspond to Fa0/1, and these MAC are in different VLAN. From this we know that Fa0/1 is the trunk interface.
From the information given by show cdp neighbors we find that there is no Fa0/5 in CDP neighbor. However, F0/5 corresponds to two MAC addresses in the same VLAN. Thus we know that Fa0/5 is connected to a Hub.  Based on the output shown, there are multiple MAC addresses from different VLANs attached to the FastEthernet 0/1 interface. Only trunks are able to pass information from devices in multiple VLANs.

66. Three switches are connected to one another via trunk ports. Assuming the default switch configuration, which switch is elected as the root bridge for the spanning-tree instance of VLAN 1?

A. the switch with the highest MAC address
B. the switch with the lowest MAC address
C. the switch with the highest IP address
D. the switch with the lowest IP address

Explanation/Reference:
Each switch in your network will have a Bridge ID Priority value, more commonly referred to as a BID. This BID is a combination of a default priority value and the switch’s MAC address, with the priority value listed first. The lowest BID will win the election process.
For example, if a Cisco switch has the default priority value of 32,768 and a MAC address of 11- 22-33-44- 55-66, the BID would be 32768:11-22-33-44-55-66. Therefore, if the switch priority is left at the default, the MAC address is the deciding factor in the root bridge election.

67. What are three advantages of VLANs? (Choose three.)

A. VLANs establish broadcast domains in switched networks.
B. VLANs utilize packet filtering to enhance network security.
C. VLANs provide a method of conserving IP addresses in large networks.
D. VLANs provide a low-latency internetworking alternative to routed networks.
E. VLANs allow access to network services based on department, not physical location.
F. VLANs can greatly simplify adding, moving, or changing hosts on the network.

Explanation/Reference:
VLAN technology is often used in practice, because it can better control layer2 broadcast to improve network security. This makes network more flexible and scalable. Packet filtering is a function of firewall
instead of VLAN.

68. Which two benefits are provided by using a hierarchical addressing network addressing scheme?  (Choose two.)

A. reduces routing table entries
B. auto-negotiation of media rates
C. efficient utilization of MAC addresses
D. dedicated communications between devices
E. ease of management and troubleshooting

Explanation/Reference:
Here are some of the benefits of hierarchical addressing: Reference: http://www.ciscopress.com/articles/article.asp p=174107

69. What is the alternative notation for the IPv6 address B514:82C3:0000:0000:0029:EC7A:0000:EC72?

A. B514 : 82C3 : 0029 : EC7A : EC72
B. B514 : 82C3 :: 0029 : EC7A : EC72
C. B514 : 82C3 : 0029 :: EC7A : 0000 : EC72
D. B514 : 82C3 :: 0029 : EC7A : 0 : EC72

Explanation/Reference:
There are two ways that an IPv6 address can be additionally compressed: compressing leading zeros and substituting a group of consecutive zeros with a single double colon (:smile. Both of these can be used in any number of combinations to notate the same address. It is important to note that the double colon (:smile can only be used once within a single IPv6 address notation. So, the extra 0’s can only be compressed once.

70. Refer to the diagram. All hosts have connectivity with one another. Which statements describe the addressing scheme that is in use in the network? (Choose three.)

A. The subnet mask in use is 255.255.255.192.
B. The subnet mask in use is 255.255.255.128.
C. The IP address 172.16.1.25 can be assigned to hosts in VLAN1
D. The IP address 172.16.1.205 can be assigned to hosts in VLAN1
E. The LAN interface of the router is configured with one IP address.
F. The LAN interface of the router is configured with multiple IP addresses.

Explanation/Reference:
The subnet mask in use is 255.255.255.128: This is subnet mask will support up to 126 hosts, which is
needed. The IP address 172.16.1.25 can be assigned to hosts in VLAN1: The usable host range in this subnet is
172.16.1.1-172.16.1.126 The LAN interface of the router is configured with multiple IP addresses: The router will need 2
subinterfaces for the single physical interface, one with an IP address that belongs in each VLAN.

71. Which two statements describe characteristics of IPv6 unicast addressing? (Choose two.)

A. Global addresses start with 2000::/3.
B. Link-local addresses start with FE00:/12.
C. Link-local addresses start with FF00::/10.
D. There is only one loopback address and it is ::1.
E. If a global address is assigned to an interface, then that is the only allowable address for the interface.

Explanation/Reference:
Below is the list of common kinds of IPv6 addresses:

35

72. The network administrator has been asked to give reasons for moving from IPv4 to IPv6. What are two valid reasons for adopting IPv6 over IPv4? (Choose two.)

A. no broadcast
B. change of source address in the IPv6 header
C. change of destination address in the IPv6 header
D. Telnet access does not require a password
E. autoconfiguration
F. NAT

Explanation/Reference:
IPv6 does not use broadcasts, and autoconfiguration is a feature of IPV6 that allows for hosts to automatically obtain an IPv6 address.

73. An administrator must assign static IP addresses to the servers in a network. For network 192.168.20.24/29, the router is assigned the first usable host address while the sales server is given the last usable host address. Which of the following should be entered into the IP properties box for the sales server?

A. IP address: 192.168.20.14 Subnet Mask: 255.255.255.248
Default Gateway: 192.168.20.9

B. IP address: 192.168.20.254 Subnet Mask: 255.255.255.0 Default Gateway:
192.168.20.1

C. IP address: 192.168.20.30 Subnet Mask: 255.255.255.248
Default Gateway: 192.168.20.25

D. IP address: 192.168.20.30
Subnet Mask: 255.255.255.240
Default Gateway: 192.168.20.17

E. IP address: 192.168.20.30 Subnet Mask: 255.255.255.240
Default Gateway: 192.168.20.25

Explanation/Reference:
For the 192.168.20.24/29 network, the usable hosts are 192.168.24.25 (router) ?192.168.24.30 (used for the sales server).

74. Which subnet mask would be appropriate for a network address range to be subnetted for up to eight LANs, with each LAN containing 5 to 26 hosts?

A. 0.0.0.240
B. 255.255.255.252
C. 255.255.255.0
D. 255.255.255.224
E. 255.255.255.240

Explanation/Reference:
For a class C network, a mask of 255.255.255.224 will allow for up to 8 networks with 32 IP addresses each (30 usable).

75. How many bits are contained in each field of an IPv6 address?

A. 24
B. 4
C. 8
D. 16

Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (smile. An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

76. What are three approaches that are used when migrating from an IPv4 addressing scheme to an  IPv6 scheme. (Choose three.)

A. enable dual-stack routing
B. configure IPv6 directly
C. configure IPv4 tunnels between IPv6 islands
D. use proxying and translation to translate IPv6 packets into IPv4 packets
E. statically map IPv4 addresses to IPv6 addresses
F. use DHCPv6 to map IPv4 addresses to IPv6 addresses

Explanation/Reference:
Several methods are used terms of migration including tunneling, translators, and dual stack. Tunnels are used to carry one protocol inside another, while translators simply translate IPv6 packets into IPv4 packets. Dual stack uses a combination of both native IPv4 and IPv6. With dual stack, devices are able to run IPv4 and IPv6 together and if IPv6 communication is possible that is the preferred protocol. Hosts can simultaneously reach IPv4 and IPv6 content.

77. Refer to the exhibit. In this VLSM addressing scheme, what summary address would be sent from router A?

36

A. 172.16.0.0 /16
B. 172.16.0.0 /20
C. 172.16.0.0 /24
D. 172.32.0.0 /16
E. 172.32.0.0 /17
F. 172.64.0.0 /16

Explanation/Reference:
Router A receives 3 subnets: 172.16.64.0/18, 172.16.32.0/24 and 172.16.128.0/18. All these 3 subnets have the same form of 172.16.x.x so our summarized subnet must be also in that form -> Only A, B or . The smallest subnet mask of these 3 subnets is /18 so our summarized subnet must also have its subnet mask equal or smaller than /18. -> Only answer A has these 2 conditions -> .

78. How is an EUI-64 format interface ID created from a 48-bit MAC address?

A. by appending 0xFF to the MAC address

B. by prefixing the MAC address with 0xFFEE

C. by prefixing the MAC address with 0xFF and appending 0xFF to it

D. by inserting 0xFFFE between the upper three bytes and the lower three bytes of the MAC address E. by prefixing the MAC address with 0xF and inserting 0xF after each of its first three bytes

Explanation/Reference:
The modified EUI-64 format interface identifier is derived from the 48-bit link-layer (MAC) address by inserting the hexadecimal number FFFE between the upper three bytes (OUI field) and the lower three bytes (serial number) of the link layer address.

79. Refer to the exhibit. What is the most efficient summarization that R1 can use to advertise its networks to R2?

37

A. 172.1.0.0/22

B. 172.1.0.0/21

C. 172.1.4.0/22

D. 172.1.4.0/24
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24

E. 172.1.4.0/25
172.1.4.128/25
172.1.5.0/24
172.1.6.0/24
172.1.7.0/24

Explanation/Reference:
The 172.1.4.0/22 subnet encompasses all routes from the IP range 172.1.4.0 ?172.1.7.255.

80. Which option is a valid IPv6 address?

A. 2001:0000:130F::099a::12a
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1

Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (smile. An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.

81. Which three are characteristics of an IPv6 anycast address? (Choose three.)

A. one-to-many communication model
B. one-to-nearest communication model
C. any-to-many communication model
D. a unique IPv6 address for each device in the group E. the same address for multiple devices in the group
F. delivery of packets to the group interface that is closest to the sending device

Explanation/Reference:
A new address type made specifically for IPv6 is called the Anycast Address. These IPv6 addresses are global addresses, these addresses can be assigned to more than one interface unlike an IPv6 unicast address. Anycast is designed to send a packet to the nearest interface that is apart of that anycast group.
The sender creates a packet and forwards the packet to the anycast address as the destination address which goes to the nearest router. The nearest router or interface is found by using the metric of a routing protocol currently running on the network. However in a LAN setting the nearest interface is found depending on the order the neighbors were learned. The anycast packet in a LAN setting forwards the packet to the neighbor it learned about first.

82. A national retail chain needs to design an IP addressing scheme to support a nationwide network. The company needs a minimum of 300 sub-networks and a maximum of 50 host addresses per subnet. Working with only one Class B address, which of the following subnet masks will support an appropriate addressing scheme? (Choose two.)

A. 255.255.255.0
B. 255.255.255.128
C. 255.255.252.0
D. 255.255.255.224
E. 255.255.255.192
F. 255.255.248.0

Explanation/Reference:
Subnetting is used to break the network into smaller more efficient subnets to prevent excessive rates of Ethernet packet collision in a large network. Such subnets can be arranged hierarchically, with the organization’s network address space (see also Autonomous System) partitioned into a tree-like structure. Routers are used to manage traffic and constitute borders between subnets. A routing prefix is the sequence of leading bits of an IP address that precede the portion of the address used as host identifier. In
IPv4 networks, the routing prefix is often expressed as a “subnet mask”, which is a bit mask covering the number of bits used in the prefix. An IPv4 subnet mask is frequently expressed in quad-dotted decimal representation, e.g., 255.255.255.0 is the subnet mask for the 192.168.1.0 network with a 24-bit routing prefix (192.168.1.0/24).

83. Refer to the exhibit. A network administrator is adding two new hosts to Switch A . Which three values could be used for the configuration of these hosts? (Choose three.)

38

A. host A IP address: 192.168.1.79
B. host A IP address: 192.168.1.64
C. host A default gateway: 192.168.1.78
D. host B IP address: 192.168.1.128
E. host B default gateway: 192.168.1.129
F. host B IP address: 192.168.1.190

84. Which IPv6 address is the all-router multicast group?

A. FF02::1
B. FF02::2
C. FF02::3
D. FF02::4

Explanation/Reference:
Well-known IPv6 multicast addresses:
Address Description
ff02::1
All nodes on the local network segment ff02::2
All routers on the local network segment

85. Refer to the exhibit. Which address range efficiently summarizes the routing table of the addresses for router Main?

39

A. 172.16.0.0/21
B. 172.16.0.0/20
C. 172.16.0.0/16
D. 172.16.0.0/18

Explanation/Reference:
The 172.16.0.0./20 network is the best option as it includes all networks from 172.16.0.0 – 172.16.16.0 and does it more efficiently than the /16 and /18 subnets. The /21 subnet will not include all the other subnets in this one single summarized address.

86. Which IPv6 address is valid

A. 2001:0db8:0000:130F:0000:0000:08GC:140B
B. 2001:0db8:0:130H::87C:140B
C. 2031::130F::9C0:876A:130B
D. 2031:0:130F::9C0:876A:130B

Explanation/Reference:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (smile. An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.

87. Which command can you use to manually assign a static IPv6 address to a router interface?

A. ipv6 autoconfig 2001:db8:2222:7272::72/64
B. ipv6 address 2001:db8:2222:7272::72/64
C. ipv6 address PREFIX_1 ::1/64
D. ipv6 autoconfig

ExplanationExplanation/Reference:
To assign an IPv6 address to an interface, use the “ipv6 address” command and specify the IP address you
wish to use.

88. Which of these represents an IPv6 link-local address?

A. FE80::380e:611a:e14f:3d69
B. FE81::280f:512b:e14f:3d69
C. FEFE:0345:5f1b::e14d:3d69
D. FE08::280e:611:a:f14f:3d69

Explanation/Reference:
In the Internet Protocol Version 6 (IPv6), the address block fe80::/10 has been reserved for link- local unicast addressing. The actual link local addresses are assigned with the prefix fe80::/64. They may be assigned by automatic (stateless) or stateful (e.g. manual) mechanisms.

89. The network administrator is asked to configure 113 point-to-point links. Which IP addressing scheme defines the address range and subnet mask that meet the requirement and waste the fewest subnet and host addresses?

A. 10.10.0.0/16 subnetted with mask 255.255.255.252
B. 10.10.0.0/18 subnetted with mask 255.255.255.252
C. 10.10.1.0/24 subnetted with mask 255.255.255.252
D. 10.10.0.0/23 subnetted with mask 255.255.255.252
E. 10.10.1.0/25 subnetted with mask 255.255.255.252

Explanation/Reference:
We need 113 point-to-point links which equal to 113 sub-networks < 128 so we need to borrow 7 bits (because 2^7 = 128).
The network used for point-to-point connection should be /30.  So our initial network should be 30 ?7 = 23.  So 10.10.0.0/23 is the correct answer.
You can understand it more clearly when writing it in binary form:
/23 = 1111 1111.1111 1110.0000 0000
/30 = 1111 1111.1111 1111.1111 1100 (borrow 7 bits)

90. A Cisco router is booting and has just completed the POST process. It is now ready to find and load an IOS image. What function does the router perform next?

A. It checks the configuration register.
B. It attempts to boot from a TFTP server.
C. It loads the first image file in flash memory.
D. It inspects the configuration file in NVRAM for boot instructions.

Explanation/Reference:
Default (normal) Boot SequencePower on Router – Router does POST – Bootstrap starts IOS load – Check configuration registerto see what mode the router should boot up in (usually 0x2102 to read startup-config in NVRAM / or 0x2142 to start in “setup-mode”) – check the startup-config file in NVRAM for boot-system commands – load IOS from Flash.

91.Refer to the exhibit. What is the meaning of the output MTU 1500 bytes?

40-cau91

A. The maximum number of bytes that can traverse this interface per second is 1500.
B. The minimum segment size that can traverse this interface is 1500 bytes.
C. The maximum segment size that can traverse this interface is 1500 bytes.
D. The minimum packet size that can traverse this interface is 1500 bytes.
E. The maximum packet size that can traverse this interface is 1500 bytes.
F. The maximum frame size that can traverse this interface is 1500 bytes.

Explanation/Reference:
The Maximum Transmission Unit (MTU) defines the maximum Layer 3 packet (in bytes) that the layer can pass onwards.

92. On a corporate network, hosts on the same VLAN can communicate with each other, but they are unable to communicate with hosts on different VLANs. What is needed to allow communication between the VLANs?

A. a router with subinterfaces configured on the physical interface that is connected to the switch
B. router with an IP address on the physical interface connected to the switch
C. a switch with an access link that is configured between the switches
D. a switch with a trunk link that is configured between the switches

Explanation/Reference:
Different VLANs can’t communicate with each other , they can communicate with the help of Layer3 router. Hence , it is needed to connect a router to a switch , then make the sub-interface on the router to connect to the switch, establishing Trunking links to achieve communications of devices which belong to different VLANs.
When using VLANs in networks that have multiple interconnected switches, you need to use VLAN trunking between the switches. With VLAN trunking, the switches tag each frame sent between switches so that the receiving switch knows to what VLAN the frame belongs. End user devices connect to switch ports that provide simple connectivity to a single VLAN each. The attached devices are unaware of any VLAN structure.
By default, only hosts that are members of the same VLAN can communicate. To change this and allow inter-VLAN communication, you need a router or a layer 3 switch. Here is the example of configuring the router for inter-vlan communication RouterA(config)#int f0/0.1
RouterA(config-subif)#encapsulation ? dot1Q IEEE 802.1Q Virtual LAN
RouterA(config-subif)#encapsulation dot1Q or isl VLAN ID RouterA(config-subif)# ip address x.x.x.x y.y.y.y

93. Which command displays CPU utilization?

A. show protocols
B. show process
C. show system
D. show version

Explanation/Reference:
The “show process” (in fact, the full command is “show processes”) command gives us lots of information about each process but in fact it is not easy to read. Below shows the output of this command (some next pages are omitted)

41

A more friendly way to check the CPU utilization is the command “show processes cpu history”, in which the total
CPU usage on the router over a period of time: one minute, one hour, and 72 hours are clearly shown

42

+ The Y- axis of the graph is the CPU utilization.+ The X-axis of the graph is the increment within the period displayed in the graph. For example, from the last graph (last 72 hours) we learn that the highest CPU utilization within 72 hours is 37% about six hours ago.

94. What two things will a router do when running a distance vector routing protocol? (Choose two.)

A. Send periodic updates regardless of topology changes.
B. Send entire routing table to all routers in the routing domain.
C. Use the shortest-path algorithm to the determine best path.
D. Update the routing table based on updates from their neighbors.
E. Maintain the topology of the entire network in its database.

Explanation/Reference:
Distance means how far and Vector means in which direction. Distance Vector routing protocols passperiodic copies of routing table to neighbor routers and accumulate distance vectors. In distance vector routing protocols, routers discover the best path to destination from each neighbor. The routing updates proceed step by step from router to router.

95. Which command is used to display the collection of OSPF link states?

A. show ip ospf link-state
B. show ip ospf lsa database
C. show ip ospf neighbors
D. show ip ospf database

Explanation/Reference:
The “show ip ospf database” command displays the link states. Here is an example:
Here is the lsa database on R2.
R2#show ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count2.2.2.2 2.2.2.2 793 0x80000003 0x004F85
210.4.4.4 10.4.4.4 776 0x80000004 0x005643 1111.111.111.111 111.111.111.111 755
0x80000005 0x0059CA 2133.133.133.133 133.133.133.133 775 0x80000005 0x00B5B1 2 Net
Link States (Area 0)
Link ID ADV Router Age Seq# Checksum10.1.1.1 111.111.111.111 794 0x80000001
0x001E8B10.2.2.3 133.133.133.133 812 0x80000001 0x004BA910.4.4.1 111.111.111.111 755
0x80000001 0x007F1610.4.4.3 133.133.133.133 775 0x80000001 0x00C31F

96. Refer to the exhibit. The technician wants to upload a new IOS in the router while keeping the existing IOS. What is the maximum size of an IOS file that could be loaded if the original IOS is also kept in flash?

43

A. 3 MB
B. 4 MB
C. 5 MB
D. 7 MB
E. 8 MB

Explanation/Reference:
In this example, there are a total of 8 MB, but 3.8 are being used already, so another file as large as 4MB can be loaded in addition to the original file.

97. If IP routing is enabled, which two commands set the gateway of last resort to the default gateway? (Choose two.)

A. ip default-gateway 0.0.0.0
B. ip route 172.16.2.1 0.0.0.0 0.0.0.0
C. ip default-network 0.0.0.0
D. ip default-route 0.0.0.0 0.0.0.0 172.16.2.1
E. ip route 0.0.0.0 0.0.0.0 172.16.2.1

Explanation/Reference:
Both the “ip default-network” and “ip route 0.0.0.0 0.0.0.0 (next hop)” commands can be used to set the
default gateway in a Cisco router.

98. Refer to the exhibit. The two exhibited devices are the only Cisco devices on the network. The serial network between the two devices has a mask of 255.255.255.252. Given the output that is shown, what three statements are true of these devices? (Choose three.)

44

A. The Manchester serial address is 10.1.1.1.
B. The Manchester serial address is 10.1.1.2.
C. The London router is a Cisco 2610.
D. The Manchester router is a Cisco 2610.
E. The CDP information was received on port Serial0/0 of the Manchester router.
F. The CDP information was sent by port Serial0/0 of the London router.

Explanation/Reference:
From the output, we learn that the IP address of the neighbor router is 10.1.1.2 and the question stated that the subnet mask of the network between two router is 255.255.255.252. Therefore there are only 2 available hosts in this network (22 ?2 = 2). So we can deduce the ip address (of the serial interface) of Manchester router is 10.1.1.1 -> The platform of the neighbor router is cisco 2610, as shown in the output – > Maybe the most difficult choice of this question is the answer E or F. Please notice that “Interface” refers to the local port on the local router, in this case it is the port of Manchester router, and “Port ID (outgoing port)” refers to the port on the neighbor router.

99. Which parameter would you tune to affect the selection of a static route as a backup, when a dynamic protocol is also being used?

A. hop count
B. administrative distance
C. link bandwidth
D. link delay
E. link cost

Explanation/Reference:
By default the administrative distance of a static route is 1, meaning it will be preferred over all dynamic routing protocols. If you want to have the dynamic routing protocol used and have the static route be used only as a backup, you need to increase the AD of the static route so that it is higher than the dynamic routing protocol.

100. Refer to the exhibit. A network associate has configured OSPF with the command:

City(config-router)# network 192.168.12.64 0.0.0.63 area 0

After completing the configuration, the associate discovers that not all the interfaces are participating in
OSPF. Which three of the interfaces shown in the exhibit will participate in OSPF according to this
configuration statement? (Choose three.)

45

A. FastEthernet0 /0
B. FastEthernet0 /1
C. Serial0/0
D. Serial0/1.102
E. Serial0/1.103
F. Serial0/1.104

Explanation/Reference:
The “network 192.168.12.64 0.0.0.63 equals to network 192.168.12.64/26. This network has: + Increment:
64 (/26= 1111 1111.1111 1111.1111 1111.1100 0000) + Network address: 192.168.12.64
+ Broadcast address: 192.168.12.127
Therefore all interface in the range of this network will join OSPF.

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Coralyn

Linda, what a stunning display of Priscilla's sunflower! Your coloring is beautiful and I love the red background. I need to use this more often, it's really one of my favgsites.Huos,Marrha

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