Cisco 642-902 Online Practice Questions and Exam Preparation

Cisco 642-902 Online Questions & Answers

• Question 71:

  Click and drag the correct techniques for transitioning networks or devices from IPv6 from the left to the target zone on the right.

  Select and Place:

  

  

• Question 72:

  Observe the exhibit.

  

  If the command variance 3 were added to RTE, which path or paths would be chosen to route traffic to network X?

  A. E-B-A
  B. E-B-A and E-C-A
  C. E-C-A and E-D-A
  D. E-B-A, E-C-A and E-D-A
  B. E-B-A and E-C-A

  ---

  Advertised distance of RTD is greater than FD of RTE-RTC-RTA, so the route through D will not be used.

• Question 73:

  Given the above OSPF network, which command will RTB use to summarize routes for the 192.168.16.0/22 supernet before injecting them into Area 0?

  

  A. area 10 range 192.168.16.0 255.255.252.0
  B. summary-address 192.168.16.0 255.255.252.0
  C. ip summary-address ospf 101 192.168.16.0 255.255.252.0
  D. area 0 range 192.168.16.0 255.255.252.0
  E. ip summary-address area 0 192.168.16.0 255.255.252.0
  A. area 10 range 192.168.16.0 255.255.252.0

  ---

  The area range command is used only with Area Border Routers (ABRs) which is router RT2 in this example. It is used to consolidate or summarize routes for an area. The result is that a single summary route is advertised to other areas by the ABR. Routing information is condensed at area boundaries. External to the area, a single route is advertised for each address range. Only Choice A specifies the correct syntax and route summarization network mask.

• Question 74:

  Refer to the exhibit.

  

  Routers R2, R3, R4, and R5 have OSPF enabled. What should be configured on the routers in area 1 to ensure that all default summary routes and redistributed EIGRP routes will be forwarded from R6 to area 1, and only a default route for all other OSPF routes will be forwarded from R5 to area 1.

  A. R5(config-router)# area 1 stub R6(config-router)# area 1 stub
  B. R5(config-router)# area 1 stub no-summary R6(config-router)# area 1 stub
  C. R5(config-router)# area 1 nssa R6(config-router)# area 1 nssa
  D. R5(config-router)# area 1 nssa no-summary R6(config-router)# area 1 nssa
  D. R5(config-router)# area 1 nssa no-summary R6(config-router)# area 1 nssa

  ---

  External RIP routes are being routed in OSPF area 1 where they are injected as type 7 so we use (area 1 NSSA) command on the ASBR(R2) and (Area 1 NSSA no-summary) command on R3 and R4. You can verify issuing the command "show ip ospf database" and you will see the type 7 lsa's on ASBR(R2) and LSA's Type 5 and 7 on both the ABR routers(R3 ,R4)

• Question 75:

  Refer to the exhibit and the partial configuration on router R2. On router R4 all RIP routes are redistributed into the OSPF domain. A second redistribution is configured on router R2 using a route map. Based on the configuration on router R2, which EIGRP external routes will be present in the routing table of R1?

  

  A. the routes originating from the RIP routing domain
  B. the routes originating from the OSPF stub area
  C. all OSPF inter and intra-area routes
  D. all routes originating from RIP and OSPF routing domains
  A. the routes originating from the RIP routing domain

  ---

  R2 sees the routes from RIP domain as external routes while it sees the routes from OSPF Stub Area as internal routers. From the output we learn that the "route-type external" is redistributed from OSPF to EIGRP (via route-map ABC) so we will see the routes from the RIP domain (external) in the routing table of R1.

  In the case we want to redistribute routes from OSPF Stub Area (Area 1) to EIGRP we need to use the "match route-type internal" command instead.

• Question 76:

  Refer to the exhibit.

  

  The 6to4 overlay tunnel configuration has been applied on each router to join isolated IPv6 networks over a IPv4 network. Which statements regarding the 6to4 overlay tunnel is true?

  A. The least significant 32 bits in the address referenced by the ipv6 route 2002::/16 Tunnel0 command will correspond to the interface E0/0 IPv4 address
  B. The least significant 32 bits in the address referenced by the ipv6 route 2002::/16 Tunnel0 command will correspond to the IPv4 address assigned to the tunnel source
  C. The configuration is invalid since the tunnel source command must be configured with an IPv6 address
  D. This is actually a configuration example of an IPv4-compatible tunnel and not a 6to4 tunnel
  E. This is actually a configuration example of an ISATAP overlay tunnel and not a 6to4 tunnel
  B. The least significant 32 bits in the address referenced by the ipv6 route 2002::/16 Tunnel0 command will correspond to the IPv4 address assigned to the tunnel source

  ---

  6to4 tunnels use IPv6 addresses that concatenate 2002::/16 with the 32-bit IPv4 address of the edge router, creating a 48-bit prefix. The tunnel interface on R1 has an IPv6 prefix of 2002:4065:4001:1::/64, where 4065:4001 is the hexadecimal equivalent of 64.101.64.1, the IPv4 address of its interface in the IPv4 network. The tunnel interface on R2 has an IPv6 prefix of 2002:4065:4101:1::/64, where 4065:4101 is the hexadecimal equivalent of 64.101.65.1, the IPv4 address of its interface in the IPv4 network. When R1 receives a packet with IPv6 destination address of 2002:4065:4101:1:: (from the left IPv6 network, for example) R1 will:

  *

  Take the IPv6 destination address of that packet (2002:4065:4101:1::) and convert it into an IPv4 address. In this case, the IPv4 address is 40.65.41.01 in hexa, which is 64.101.65.1 in decimal format.

  *

  R1 encapsulates the IPv6 packet in an IPv4 packet with a destination address of 64.101.65.1; the packet is routed normally through the IPv4 network to R2

  *

  R2 receives the IPv4 packet, decapsulates and routes it normally to its final IPv6 destination.

• Question 77:

  Refer to the exhibit.

  

  R1 and R2 have been configured to share routing information via EIGRP. What will be the result of the configuration section shown for R2?

  A. Any routes learned by R2 from the interface tied to the 172.16.0.0 network will not be advertised to neighbors on the 192.168.2.0 network.
  B. Only routes learned by R2 from the interface tied to the 172.16.0.0 network will be advertised to neighbors on the 192.168.2.0 network.
  C. Only the 172.16.0.0 network will be advertised to neighbors on the 192.168.2.0 network.
  D. All networks, except the 172.16.0.0 network will be advertised to neighbors on the 192.168.2.0 network.
  C. Only the 172.16.0.0 network will be advertised to neighbors on the 192.168.2.0 network.

• Question 78:

  Which option is true regarding the synchronization rule?

  A. Do not use or internally advertise a route until the route is learned from a source other than BGP.
  B. Do not use or advertise a route until the route is learned from a BGP peer.
  C. Do not use or advertise routes marked PARTIAL.
  D. Wait until a CONFIRM message is received before using routes from BGP neighbors.
  A. Do not use or internally advertise a route until the route is learned from a source other than BGP.

  ---

  The complete synchronization rule is "A BGP router should not use, or advertise to an external neighbor, a route learned by IBGP, unless that route is local or is learned from the IGP."

  With the default of synchronization disabled, BGP can use and advertise to external BGP neighbors routes learned from an IBGP neighbor that are not present in the local routing table

  The "synchronization" here means "synchronization between iBGP with its IGP (such as OSPF, EIGRP...)

  You can disable synchronization if one of the following conditions is true:

  Your AS does not pass traffic from one AS to another AS.

  All the transit routers in your AS run BGP.

  Note: BGP synchronization is disabled by default in Cisco IOS Software Release 12.2(8)T and later.

• Question 79:

  Refer to the exhibit.

  

  What additional commands should be used to configure OSPF area 5 as a Totally Stubby area?

  A. area 0 stub on routers R4 and R5
  B. area 5 stub on routers R4 and R5
  C. area 5 stub no-summary on routers R4 and R5
  D. area 0 stub no-summary on router R4 and area 5 stub no-summary on router R5
  E. area 5 stub no-summary on router R4 and area 5 stub on router R5
  E. area 5 stub no-summary on router R4 and area 5 stub on router R5

  ---

  To define a totally stub area, use the area area-id stub no-summary command on the ABR (in OSPF router configuration) and the area area-id stub on the totally stub router. The ABR will inject a default route into the area so routers in this type of area only see routing information local to their area, plus a default route pointing to the ABR, from which they can reach all other areas and all other networks

• Question 80:

  Refer to the exhibit. EIGRP is configured with the default configuration on all routers. Autosummarization is enabled on routers R2 and R3, but it is disabled on router R1. Which two EIGRP routes will be seen in the routing table of router R3? (Choose two.)

  

  A. 10.0.0.0/8
  B. 10.10.0.0/16
  C. 10.10.10.0/24
  D. 172.16.0.0/16
  E. 172.16.0.0/24
  F. 172.16.10.0/24
  C. 10.10.10.0/24
  D. 172.16.0.0/16

  ---

  EIGRP performs an auto-summarization each time it crosses a border between two different major networks. In this case all different networks are in different major networks so EIGRP will perform auto-summarization when it exits an interface. But R1 has been configured with "no auto-summary" command so EIGRP will not summarize on S0 interface of R1. So the routing table of R2 will have the network 10.10.10.0/24 (not be summarized).

  When exiting S1 interface of R2, EIGRP summarizes network 172.16.10.0/24 into the major 172.16.0.0/16 network but it does not summarize network 10.10.10.0/24 because it is not directly connected with this network. Therefore in the routing table of R3 there will have:

  +

  Network 10.10.10.0/24 ( not summarized)

  +

  Network 172.16.0.0/16 (summarized)

  -> C and D are correct.

  Note: I simulated this question on GNS3, you can see the final outputs of the "show ip route" commands on these routers (I connected these routers via FastEthernet, not Serial interfaces so the outputs are slightly different but the main points

  are not changed).