Question 1.
How do you make OSPF do automatic classful summarization?

a) Explicitly code the (non-default) router subcommand auto-summary
b) Use network statements without the wildcard mask
c) OSPF is not capable of automatic classful summarization.
d) Enable automatic summarization on the area border routers.

Answer

Question 2.
When does OSPF do periodic announcements of routing information?

a) Every 30 seconds
b) When the timer associated with a LSA expires
c) Every 90 seconds
d) OSPF never does periodic broadcasts.

Answer

Question 3.
Refer to the figure. Which set of statements will put all the interfaces into OSPF area 0.0.0.1?

network 0.0.0.0 255.255.255.255 area 0.0.0.0
network 0.0.0.0 255.255.255.255 area 0.0.0.1

network 0.0.0.0         255.255.255.255 area 0.0.0.0
network 192.168.1.1     0.0.0.15        area 0.0.0.1
network 192.168.255.253 0.0.0.3         area 0.0.0.1
network 192.168.2.1     0.0.0.255       area 0.0.0.1

network 192.168.1.0     0.0.0.0         area 0.0.0.1
network 192.168.255.252 0.0.0.0         area 0.0.0.1
network 192.168.2.0     0.0.0.0         area 0.0.0.1
network 0.0.0.0         255.255.255.255 area 0.0.0.0

network 192.168.1.1     0.0.0.0         area 0.0.0.1
network 192.168.255.253 0.0.0.0         area 0.0.0.1
network 192.168.2.1     0.0.0.0         area 0.0.0.1
network 0.0.0.0         255.255.255.255 area 0.0.0.0

Answer

Answers

Question 1.
How do you make OSPF do automatic classful summarization?

a) Explicitly code the (non-default) router subcommand auto-summary
b) Use network statements without the wildcard mask
c) OSPF is not capable of automatic classful summarization.
d) Enable automatic summarization on the area border routers.

Answer
c) OSPF is not capable of automatic classful summarization.

Explanation
OSPF, unlike EIGRP, has no concept of classful summarization -- or automatic summarization of any type. You can achieve equivalent behavior with manual summarization on classful boundaries at area border routers, but OSPF itself was designed to work with classless addressing.
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Question 2.
When does OSPF do periodic announcements of routing information?

a) Every 30 seconds
b) When the timer associated with a LSA expires
c) Every 90 seconds
d) OSPF never does periodic broadcasts.

Answer
b) When the timer associated with a LSA expires

Explanation
RIP always sends UDP broadcasts for its updates, at approximately 30-second intervals. IGRP broadcasts at 90-second intervals. OSPF does not periodically announce its routing table, but it does periodically set the age field in potentially expired LSAs and reflood these LSAs to see if they still are active.
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Question 3.
Refer to the figure. Which set of statements will put all the interfaces into OSPF area 0.0.0.1?

network 0.0.0.0 255.255.255.255 area 0.0.0.0
network 0.0.0.0 255.255.255.255 area 0.0.0.1

network 0.0.0.0         255.255.255.255 area 0.0.0.0
network 192.168.1.1     0.0.0.15        area 0.0.0.1
network 192.168.255.253 0.0.0.3         area 0.0.0.1
network 192.168.2.1     0.0.0.255       area 0.0.0.1

network 192.168.1.0     0.0.0.0         area 0.0.0.1
network 192.168.255.252 0.0.0.0         area 0.0.0.1
network 192.168.2.0     0.0.0.0         area 0.0.0.1
network 0.0.0.0         255.255.255.255 area 0.0.0.0

network 192.168.1.1     0.0.0.0         area 0.0.0.1
network 192.168.255.253 0.0.0.0         area 0.0.0.1
network 192.168.2.1     0.0.0.0         area 0.0.0.1
network 0.0.0.0         255.255.255.255 area 0.0.0.0

network 192.168.1.1     0.0.0.0         area 0.0.0.1
network 192.168.255.253 0.0.0.0         area 0.0.0.1
network 192.168.2.1     0.0.0.0         area 0.0.0.1
network 0.0.0.0         255.255.255.255 area 0.0.0.0

Explanation
Choice A will put everything into area 0.0.0.0 because the area 0.0.0.0 statement will match first. The same problem exists in choice B.

The first three statements in choice C match one and only one address, which I find to be a wise practice. Unfortunately, they match the address of the subnet itself, not any interface on it.
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