Chapter 11

"Do I Know This Already?"

1.	C
2.	A
3.	A
4.	A and C
5.	B
6.	C
7.	A and B
8.	A, B, C
9.	C
10.	C

11.	B
12.	B, C, D
13.	B
14.	C
15.	A, B, C
16.	E

Q&A

1.	Answer: Passive interfaces Static routes Default routes The null interface Distribute lists Route maps
2.	Answer: If there is a WAN link where the cost of the link is based on network traffic. This might also have the added disincentive of being a WAN link that is a dial-on-demand link, which is raised and maintained by the presence of traffic attempting to flow across the interface. When trying to prevent routing loops.
3.	EIGRP will automatically redistribute between IGRP and EIGRP if the AS number is the same.
4.	The show ip route command displays two numbers in brackets: the route metric, followed by the administrative distance.
5.	When there is more than one routing protocol for IP running within the organization and when every part of the network needs connectivity to all the networks.
6.	Overlapping routing protocols will increase network traffic, router CPU processing, and memory requirements because of the additional protocol updates. The additional traffic and CPU and memory requirements complicate the routing process. The decision is not simply between multiple paths, but also between the various routing protocols that are advertising the paths.

7.	Lower metrics are preferred when choosing among multiple paths to a remote network.
8.	Answer: The organization is transitioning from one routing protocol to another because the network has grown and there is a need for a more sophisticated protocol that will scale. There is a mix of vendors used within the network, and some equipment does not support the preferred solution. The organization is transitioning from a set of smaller networks to form one large enterprise network. After a merger or a takeover, redistribution allows the status quo to be maintained while planning for a combined network. There are ideological differences among the different network administrators.
9.	Answer: Suboptimal paths chosen. Routing loops. Convergence time increases.
10.	Answer: Router(config-router)#distribute-list {access-list-number \| name} out [interface-name \| routing-process \| autonomous-system-number]
11.	A passive interface is an interface that listens to updates but that will not propagate updates for a given routing protocol. OSPF and EIGRP will not learn routes over a passive interface because they cannot exchange hellos.
12.	There is no way to algorithmically compare OSPF cost to EIGRP metric, nor—with the exception of IGRP and EIGRP—is there a way to compare any two routing protocols. Routes from different protocols are therefore chosen on the basis of a Cisco-defined ranking, called administrative distance.
13.	If two routing protocols both have a path to the same destination, the path for the routing table will be selected based on administrative distance. Potentially, this path is not the best path.
14.	Costs are lost during redistribution, and setting a default metric provides some idea of how a route should be preferred. Also, RIP and EIGRP set the default metric to infinity. If you do not specify a default metric, nothing will be passed.

15.	Answer: Router(config-router)#distance weight [address mask] [access-list \| name] [ip] For EIGRP, the administrative distance command is Router(config)#distance eigrp internal-distance external-distance