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Answers to Assessment Test

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26.

B. Sequence numbers are assigned in increments of five when no
sequence number was assigned when the prefix list statements were
configured. See Chapter 9 for more information.

27.

A. Route summarization, which works best with contiguous address
space, reduces the memory and processor burden on routers by repre-
senting multiple subnets in a single route advertisement. For more
information, see Chapter 3.

28.

A, B. BGP should be used when multi-homing and when connecting
multiple ISPs. For more information, see Chapter 7.

29.

A. SPF is the type of path created by the Dijkstra algorithm. See
Chapter 4 for more information.

30.

C. The IOS command show ip ospf process-id shows area infor-
mation, such as the identity of the area border router (ABR) or auton-
omous system boundary router (ASBR). For more information, see
Chapter 5.

31.

A, B, C, E. Confederations use iBGP on routers in sub-ASes and then
use eBGP to connect the sub-ASes. The sequence number is used in
prefix lists. The confederation identifier is the number assigned to all
the routers to identify that all the routers in the confederation using
sub-ASes reside in the same autonomous system. See Chapter 9 for
more information.

32.

C, D. There must always a DR and a BDR for each multi-access seg-
ment. See Chapter 4 for more information.

33.

C. The MED attribute is used to inform other external AS routers as
to which route to use in order to receive traffic. For more information,
see Chapter 8.

34.

A. If the IGRP and EIGRP processes are both running on the same
router, their routes will be automatically redistributed if their
process-ids

are equal. This is possible because IGRP and EIGRP use

very similar metrics. Note that in some of the literature, the process-
id

may be referred to as an Autonomous System. For more informa-

tion, see Chapter 10.

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