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Chapter 6
Answers to Review Questions
D. One of the great benefits of EIGRP is that it advertises only
changes, and only when there is a change in the network topology
does it recalculate routes. Hello packets continue to be sent in order
to verify that all the attached links are still connected and did not go
A, B, C. The neighbor table uses the smooth round-trip timer
(SRTT), the retransmission timer (RTO), and the hold timer to track
its neighboring routers. The FwdDelay and MaxAge timers are both
used by the Spanning Tree Protocol to keep Layer 2 switches from cre-
ating data loops.
C. The link will always be in Active mode regardless of the link cost
because there is no other feasible successor. If the link goes down,
there is no other redundant link to use.
A. This is a trick question. IP is a routed protocol but TCP is not.
Both IPX and AppleTalk are examples of routed protocols.
A, C. Link-state routing protocols use the Hello protocol and update
neighbors of changes without sending the entire routing or topology
D. Static routes must always be redistributed by a routing protocol
and always have the smallest administrative distance.
D. Passive interfaces are used for such interfaces as BRI, where you
do not want to have routing updates sent out the interface. If routing
updates were sent out of a BRI interface, the interface would never dis-
connect. You can also configure the routing traffic to be uninteresting
traffic to perform a similar function.
A, B. The feasible successor, which would be the path with the next-
lowest metric, would be chosen. Or, if the router has not learned of
any secondary routes, the router will query its neighbors to see if they
know of any routes.
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