Cisco 642-902 Online Practice Questions and Exam Preparation

Cisco 642-902 Online Questions & Answers

• Question 251:

  Refer to the exhibit.

  

  On all routers in the network, EIGRP has been configured for load balancing across the three links. However, traffic destined for Network B from R1 is only load balanced over paths R1- R2-R5 and R1-R3-R5. What is the cause of the problem?

  A. EIGRP will not select more than two links for unequal cost path load balancing.
  B. Because the path has a different link type, EIGRP will not select path R1-R4-R5 for load balancing.
  C. Because Router R4 is not a feasible successor, EIGRP will not select path R1-R4-R5 for load balancing.
  D. EIGRP will not select path R1-R4-R5 for load balancing unless the value of the variance parameter is increased.
  C. Because Router R4 is not a feasible successor, EIGRP will not select path R1-R4-R5 for load balancing.

  ---

  Since R4 is not configured as a feasible successor, EIGRP will not select that path for load balancing. IN EIGRP, you need to configure feasible successor to enable load balancing on the path.

• Question 252:

  What happens when an IPv6 enabled router running 6to4 must send a packet to a remote destination and the next hop is the address of 2002::/16?

  A. The IPv6 packet has its header removed and replaced with an IPv4 header
  B. The IPv6 packet is encapsulated in an IPv4 packet using an IPv4 protocol type of 41
  C. The IPv6 packet is dropped because that destination is unable to route IPv6 packets
  D. The packet is tagged with an IPv6 header and the IPv6 prefix is included
  B. The IPv6 packet is encapsulated in an IPv4 packet using an IPv4 protocol type of 41

  ---

  6to4 and Teredo are dynamic tunneling techniques used by desktop operating systems to help their users gain access to the IPv6 Internet. These techniques tunnel the IPv6 packets within IPv4 packets. The 6to4 method places the IPv6 packets within IPv4 protocol 41 packets. The Teredo method places the IPv6 packets within IPv4 packets with a UDP 3544 header. Reference: http://www.networkworld.com/community/node/47345

• Question 253:

  Study the configuration presented in the exhibit carefully.

  

  What is the objective of the route map named test?

  A. marks all prefixes received from the 10.1.1.1 neighbor with a MED of 200
  B. marks the 10.0.0.0/8 prefix received from the 10.1.1.1 neighbor with a MED of 200
  C. marks the 10.0.0.0/8 prefix advertised to the 10.1.1.1 neighbor with a MED of 200
  D. marks all prefixes advertised to the 10.1.1.1 neighbor with a MED of 200
  C. marks the 10.0.0.0/8 prefix advertised to the 10.1.1.1 neighbor with a MED of 200

  ---

  The Multiple-exit-discriminator (MED) attribute is an optional nontransitive attribute, type code 4. MED informs external neighbors about the preferred path into an AS that has multiple entry points. A lower MED is preferred over a higher MED. Unlike Local Preference, the MED attribute is exchanged between autonomous systems, but a MED attribute that comes into an AS does not leave the AS. When an update enters the AS with a certain MED value, that value is used for decision making within the AS. When BGP forwards the routing update to another AS, the MED is reset to zero. This is true unless the outgoing MED is set to a specific value. Example: RTB(config)#route-map setmedout permit 10 RTB(config-route-map)#set metric 50 RTB(config)#router bgp 400

• Question 254:

  Refer to the exhibit.

  

  In the show ipv6 route output, what would the metric be for a summary route that summarizes all three OSPFv3 routes displayed?

  A. 20
  B. 40
  C. 100
  D. 120
  E. 140
  F. 160
  C. 100

  ---

  The cost of the summarized routes is the highest cost of the routes being summarized. In fact, in the old RFC 1583 standard, the cost of the summary route was the cost of the lowest metric. But when OSPF was updated in RFC 2178 and RFC 2328, the summary route should have the same cost as the highest-cost summarized route. In this case, the highest-cost is 100 according to the second entry.

• Question 255:

  Refer to the exhibit. A new TAC engineer comes to you for advice. The engineer wants to configure RIPv2- OSPF two-way redistribution while avoiding routing loops. Which two additions to the router B1 configuration should the engineer make? (Choose two.)

  

  A. access-list 40 deny 172.16.1.0 0.0.0.255 access-list 40 permit any router rip redistribute ospf 100 metric 5 distribute-list 40 out ospf 100
  B. ip prefix-list rip_routes permit 172.16.1.16/25 ge 26 le 28 route-map redis-ospf deny 10 match ip address prefix-list rip_routes router rip redistribute ospf 10 route-map redis-ospf subnets
  C. ip prefix-list rip-to-ospf permit 10.1.1.8/25 ge 26 le 28 route-map redis-rip deny 20 match ip address prefix-list rip-to-ospf router ospf 100 redistribute rip route-map redis-rip subnets
  D. access-list 15 permit 10.1.1.0 0.0.0.63 access-list 15 permit any route-map redis-rip deny 10 match ip address 15 route-map redis-rip permit 20 router ospf 100 redistribute rip route-map redis-rip subnets
  A. access-list 40 deny 172.16.1.0 0.0.0.255 access-list 40 permit any router rip redistribute ospf 100 metric 5 distribute-list 40 out ospf 100
  D. access-list 15 permit 10.1.1.0 0.0.0.63 access-list 15 permit any route-map redis-rip deny 10 match ip address 15 route-map redis-rip permit 20 router ospf 100 redistribute rip route-map redis-rip subnets

  ---

  B1 is not the only router that redistributes between RIP and OSPF. The "small" router below B1 can be configured for this task too so B1 can try to redistribute networks advertised by that "small" router again. Therefore it is necessary to filter out networks that have been advertised by the "small" router. For example, we need to prevent network 172.16.1.0/24 from advertised back into RIPv2 or network 10.1.1.0/26 from advertised back into OSPF. Notice that all networks in OSPF domain (including 10.1.1.8/30, 10.1.1.12/30, 10.1.1.48/28, 10.1.1.32/28) can be summarized as 10.1.1.0/26 and all networks in RIP domain (including 172.16.1.24/30, 172.16.1.20/30, 172.16.1.32/28, 172.16.1.48/28) can be summarized as 172.16.1.0/24 -> answers A and D are correct.

  In answer B, the command "ip prefix-list rip_routes permit 172.16.1.16/25 ge 26 le 28 means:

  +

  First check the first 25 bits of the address -> this will allow addresses from 172.16.1.0 to 172.16.1.127

  +

  If those match then check the subnet mask, which in this case can be GREATER THAN or EQUAL to 26 bits and LESS THAN or EQUAL to 28 bits -> meaning that /26, /27, /28 subnet masks would match. For example, networks 172.16.1.0/26; 172.16.1.16/28 would match (but notice networks 172.16.1.0/25; 172.16.1.128/26 wouldn't).

  

  In the "ip prefix-list rip_routes permit 172.16.1.16/25 ge 26 le 28, the prefix-list "rip_routes" only covers networks 172.16.1.32/28 and 172.16.1.48/28 but can't cover networks 172.16.1.24/30 and 172.16.1.20/30. Also, the OSPF process in the "redistribute" command should be 100, not 10.

  Same problem as answer B, the prefix-list in answer C can't cover networks 10.1.1.8/30 and 10.1.1.12/30 .

• Question 256:

  Which statement is true concerning 6to4 tunneling?

  A. IPv4 traffic is encapsulated with an IPv6 header.
  B. The edge routers can use any locally configured IPv6 address.
  C. Hosts and routers inside a 6to4 site will need a special code.
  D. An edge router must use IPv6 address of 2002::/16 in its prefix.
  D. An edge router must use IPv6 address of 2002::/16 in its prefix.

  ---

  6to4 tunnels use IPv6 addresses that concatenate 2002::/16 with the 32-bit IPv4 address of the edge router, creating a 48-bit prefix.

• Question 257:

  Refer to the exhibit.

  

  In the network diagram, Area 1 is defined as a stub area. Because redistribution is not allowed in the stub area, EIGRP routes cannot be propagated into the OSPF domain. How does defining area 1 as a not-so-stubby area (NSSA) make it possible to inject EIGRP routes into the OSPF NSSA domain?

  A. by creating type 5 LSAs
  B. by creating type 7 LSAs
  C. by creating a link between the EIGRP domain and the RIP domain, and redistributing EIGRP into RIP D. by manually changing the routing metric of EIGRP so that it matches the routing metric of OSPF
  B. by creating type 7 LSAs

• Question 258:

  The company network is in the process of migrating the IP address scheme to use IPv6. Which of the following address types are associated with IPv6? (Select three)

  A. Unicast
  B. Private
  C. Broadcast
  D. Public
  E. Multicast
  F. Anycast
  A. Unicast
  E. Multicast
  F. Anycast

  ---

  Reference:

  http://www.cisco.com/en/US/solutions/collateral/ns340/ns414/ns742/ns824/sbaBN_IPv6addr G.pdf ( see page 3, IPv6 address types)

• Question 259:

  Refer to the exhibit.

  

  Routers R1 and R2 are running EIGRP and have converged. On the basis of the information that is presented, which statement is true?

  A. All outgoing routing updates from router R1 to router R2 will be suppressed, but the inbound updates will continue to be received.
  B. All incoming routing updates from R2 will be suppressed, but the outgoing updates will continue to be sent.
  C. Both outgoing and incoming routing updates on R1 will be stopped because of the passive- interface Serial0/0 configuration statement.
  D. Both outgoing and incoming routing updates on R1 will be permitted because the distribute-list 20 out Serial0/0 command cannot be used with association with the outgoing interface.
  C. Both outgoing and incoming routing updates on R1 will be stopped because of the passive- interface Serial0/0 configuration statement.

  ---

  You can use the passive-interface command to control the advertisement of routing information. The command enables the suppression of routing updates over some interfaces while it allows updates to be exchanged normally over other interfaces. With most routing protocols, the passive-interface command restricts outgoing advertisements only. However, when used with Enhanced Interior Gateway Routing Protocol (EIGRP), the effect is slightly different. With EIGRP running on a network, the passive- interface command stops both outgoing and incoming routing updates, since the effect of the command causes the router to stop sending and receiving hello packets over an interface. Reference: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f0a.shtml

• Question 260:

  When an OSPF design is planned, which implementation can help a router not have memory resource issues?

  A. Have a backbone area (area 0) with 40 routers and use default routes to reach external destinations.
  B. Have a backbone area (area 0) with 4 routers and 30,000 external routes injected into OSPF.
  C. Have less OSPF areas to reduce the need for interarea route summarizations.
  D. Have multiple OSPF processes on each OSPF router. Example, router ospf 1, router ospf 2.
  A. Have a backbone area (area 0) with 40 routers and use default routes to reach external destinations.

  ---

  Memory issues usually come up when too many external routes are injected in the OSPF domain. A backbone area with 40 routers and a default route to the outside world would have less memory issues compared with a backbone area with 4 routers and 33,000 external routes being injected into OSPF. Router memory could also be conserved by using a good OSPF design. Summarization at the area border routers and use of stub areas could further minimize the number of routes exchanged.

  The total memory used by OSPF is the sum of the memory used in the routing table ( show ip route summary ) and the memory used in the LSDB. The following numbers are a "rule of thumb" estimate. Each entry in the routing table will consume between approximately 200 and 280 bytes plus 44 bytes per extra path. Each LSA will consume a 100 byte overhead plus the size of the actual LSA, possibly another 60 to 100 bytes (For router links, this depends on the number of interfaces on the router). These amounts should be added to memory already used by other processes and by the IOS itself.

  If you really want to know the exact number, you can do a show memory with and without OSPF being turned on. The difference in the processor memory used would be the answer.