CCNA 3 (Chapter8)

Fill in the blank. The wildcard mask that is used to advertise exactly the network 192.168.160.0 with subnet mask 255.255.240.0 is __________

0.0.15.255 Refer to curriculum topic: 8.2.2 The easiest method for calculating a wildcard mask is to subtract the network subnet mask from 255.255.255.255. In this case we have 255.255.255.255 - 255.255.240.0.

Which three statements describe the similarities between OSPFv2 and OSPFv3? (Choose three.)

1. They both are link-state protocols. 2. They both share the concept of multiple areas 3. They both use the same DR/BDR election process. Refer to curriculum topic: 8.3.1 Only OSPFv2 messages are sourced from the IP address of the exit interface; OSPFv3 uses the link-local address of the exit interface. Only OSPFv3 uses IPsec; OSPFv2 uses plain text or MD5 authentication. Unicast routing is enabled by default only with OSPFv2.

hat are three entries that are displayed by the show ip ospf neighbor command? (Choose three.)

1. the router ID of the neighboring routers 2. the OSPF state of each interface 3. the IP address of the neighbor router interface to which this router is directly connected Refer to curriculum topic: 8.2.4 The route metric and neighbor next hop address are routing table entries that are displayed by the show ip route command. The show ip ospf neighbor command does not display the OSPF process ID or the OSPF area number.

Fill in the blank. Refer to the exhibit. With the default metric settings, the OSPF cost for R1 to reach the network 172.16.1.0 is ________

1564 Refer to curriculum topic: 8.2.3 The OSPF cost metric is the accumulated value from R1 to network 172.16.1.0. The cost for the first link is 100,000,000/64,000 (1562). The cost for the second link is 100,000,000/100,000,000 (1). The cost for the third link is 100,000,000/100,000,000 (1). The OSPF cost metric from R1 to 172.16.1.0 is therefore 1564.

The OSPF hello timer has been set to 15 seconds on a router in a point-to-point network. By default, what is the dead interval on this router?

60 seconds Refer to curriculum topic: 8.1.2 By default, the dead interval is calculated as 4 times the hello interval.

Which statement is correct about multiarea OSPF?

Arranging routers into areas partitions a large autonomous system in order to lighten the load on routers. Refer to curriculum topic: 8.1.1 A company with one large autonomous system or AS can be divided into smaller areas. When this occurs and the OSPF routing protocol is implemented, the design is called multiarea OSPF. Multiarea OSPF decreases the frequency of the SPF calculation, thus lightening the load on the router. In a single area OSPF design, all the routers are located in area 0 or the backbone area.

Which statement describes a difference or similarity between OSPFv2 and OSPFv3?

Both OSPFv2 and OSPFv3 use multicast destination addresses for link-state packets. Refer to curriculum topic: 8.3.1 OSPFv2 uses the router configuration network command to advertise networks. OSPFv3 uses the ipv6 ospf process-id area area-id interface configuration command. Both OSPFv2 and OSPFv3 use a 32 bit router ID. Both OSPFv2 and OSPFv3 require the DR/BDR election to occur on multiaccess networks. Neither protocol requires a DR/BDR election for point-to-point networks.

Which OPSF packet contains the different types of link-state advertisements?

LSU Refer to curriculum topic: 8.1.2 Link-state update (LSU) packets contain different types of link-state advertisements (LSAs). The LSUs are used to reply to link-state requests (LSRs) and to announce new information.

Fill in the blank. Do not use abbreviations. To quickly verify OSPFv3 configuration information including the OSPF process ID, the router ID, and the interfaces enabled for OSPFv3, you need to issue the command

Show ipv6 protocols Refer to curriculum topic: 8.3.3

A network administrator configures a loopback interface as the OSPF router ID with the IP address of 192.168.1.1/30. What could be the consequence of using this 30-bit mask for the loopback interface?

This loopback interface may be advertised as a reachable network. Refer to curriculum topic: 8.2.1 A loopback interface used as an OSPF router ID normally uses a 32-bit mask that creates a host route. This route is not advertised as a route to other routers unless a network statement including this interface is added.

Fill in the blank. The OSPF Type 1 packet is the __________ packet

hello Refer to curriculum topic: 8.1.2 There are 5 different types of packets that are used in OSPF. Type 1 is the hello packet.

The command clear ip ospf ____________ forces a router with a new or changed router ID to form new adjacencies.

process Refer to curriculum topic: 8.2.1 An active OSPF router will not allow the router ID to be changed until it is reloaded or the OSPF process is cleared. Clearing the current process forces the router to renegotiate adjacencies and advertise its new information.

A network technician issues the following commands when configuring a router: R1(config)# router ospf 11 R1(config-router)# network 10.10.10.0 0.0.0.255 area 0 What does the number 11 represent?

the OSPF process ID on R1 Refer to curriculum topic: 8.2.1 There is no autonomous system number to configure on OSPF. The area number is located at the end of the network statement. The cost of a link can be modified in the interface configuration mode. The process ID is local to the router.