Cisco 642-902 Online Practice Questions and Exam Preparation

Cisco 642-902 Online Questions & Answers

• Question 371:

  Refer to the exhibit.

  

  Which two statements are true about the router configuration? (Choose two.)

  A. This configuration allows applications on the same segment to communicate via IPv4 or IPv6.
  B. This configuration is referred to as a dual-stack 6to4 tunnel.
  C. This configuration is referred to as a dual stack.
  D. This configuration will attempt to route packets using IPv4 first, and if that fails, then IPv6.
  A. This configuration allows applications on the same segment to communicate via IPv4 or IPv6.
  C. This configuration is referred to as a dual stack.

  ---

  This router demonstrates an example of an IPv6 Dual Stack configuration. Dual stack (Figure 1 below) runs both IPv4 and IPv6 protocol stacks on a router in parallel, making it similar to the multiprotocol network environments of the past,

  which often ran Internetwork Packet Exchange (IPX), AppleTalk, IP, and other protocols concurrently. The technique of deploying IPv6 using dual-stack backbones allows IPv4 and IPv6 applications to coexist in a dual IP layer routing

  backbone. The IPv4 communication uses the IPv4 protocol stack, and the IPv6 communication uses the IPv6 stack. As a transition strategy, dual stack is ideal for campus networks with a mixture of IPv4 and IPv6 applications.

  Figure 1: Dual-Stack Example

  

  Reference: http://www.cisco.com/en/US/products/ps6553/products_white_paper0900aecd805c54d0.sht ml

• Question 372:

  Refer to the exhibit.

  

  Which command would verify if PBR reacts to packets sourced from 172.16.0.0/16?

  A. show ip route
  B. show policy-map
  C. show access-lists
  D. show route-map
  D. show route-map

  ---

  The "show route-map "route-map name" displays the policy routing match counts so we can learn if PBR reacts to packets sourced from 172.16.0.0/16 or not.

  

• Question 373:

  

  The R2 router has lost connectivity to R1. The following is R1s current route table:

  The company and the company network have both been growing rapidly. Multiple adds, moves and changes have been applied to the network. Your boss has asked you to troubleshoot a recent OSPF synchronization problem that has arisen. There have been synchronization problems at separate locations in the OSPF area 0. There have been reported link failures during the rapid growth of the company network. You are required to resolve the OSPF problem. OSPF must be able to converge when the network changes. Refer to the information above to answer the following question.

  

  Which expected route is missing from R1s route table based on the topology during the maintenance period?'

  A. o 172.16.0.0 [110/2] via 10.138.43.1, 00:00:09, FastEthernet0/0
  B. o IA 9.152.105.122 [110/3] via 10.138.43.1, 00:00:09, FastEthernet0/0
  C. o IA 10.138.0.0 [110/3] via 10.138.43.1, 00:00:09, FastEthernet0/0
  D. o IA 10.249.0.0 [110/2] via 10.138.43.1, 00:00:09, FastEthernet0/0
  E. o IA 4.249.113.59 [110/2] via 10.138.43.1, 00:00:09, FastEthernet0/0
  F. o 8.187.175.82 [110/3] via 10.138.43.1, 00:00:09, FastEthernet0/0
  F. o 8.187.175.82 [110/3] via 10.138.43.1, 00:00:09, FastEthernet0/0

  ---

  0 8.287.175.82 [110/3] is not to be seen in the R1 current route table which means it has lost connectivity via 10.138.43.1. Also 10.0.0.0/30 has only 1 subnet.

• Question 374:

  Refer to the exhibit. Router C was configured so that it could form an adjacency with three OSPF neighbors, one connected to each of its three physical interfaces.

  

  Which statement is correct about router C?

  A. It is configured and functioning correctly as an OSPF internal router.
  B. It is configured and functioning correctly as an ABR attached to stub area 4.
  C. It is configured and functioning correctly as an ASBR attached to external area 4.
  D. It is configured and functioning correctly as an ABR attached to totally stubby area 4.
  E. It is not configured correctly to function as specified.
  D. It is configured and functioning correctly as an ABR attached to totally stubby area 4.

  ---

  From the output of the "show ip ospf" command we notice 2 lines:

  +

  It is an area border router

  +

  It is a stub area, no summary LSA in this area (in Area 4)

  Therefore we can conclude RouterC is an ABR and it is attached to a totally stubby area (with no summary LSA advertised).

• Question 375:

  In a comparison of an IPv4 header with an IPv6 header, which three statements are true? (Choose three.)

  A. An IPv4 header includes a checksum. However, an IPv6 header does not include one.
  B. A router has to recompute the checksum of an IPv6 packet when decrementing the TTL.
  C. An IPv6 header is half the size of an IPv4 header.
  D. An IPv6 header has twice as many octets as an IPv4 header.
  E. An IPv6 header is simpler and more efficient than an IPv4 header.
  F. The 128-bit IPv6 address makes the IPv6 header more complicated than an IPv4 header.
  A. An IPv4 header includes a checksum. However, an IPv6 header does not include one.
  D. An IPv6 header has twice as many octets as an IPv4 header.
  E. An IPv6 header is simpler and more efficient than an IPv4 header.

  ---

  The image below shows the differences between an IPv4 header and an IPv6 header:

  

  (Reference and a good resource, too: http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_9-3/ipv6_internals.html)