Question 1.
Which of the following statements are true regarding the ISIS backbone?
(Choose 2)

a) It must be contiguous.
b) It does not need to be contiguous if virtual links are used to connect portioned areas.
c) It consists of all routers, both Level 1/2 and Level-2-only, that have Level 2 adjacencies.
d) It consists of all Level-2-only routers.

Answer

Question 2.
In a pre-RFC 2966 ISIS network, Level 1 areas are most comparable to which of the following OSPF area types?

a) Normal Area
b) Stub Area
c) Not So Stubby Area (NSSA)
d) Totally Stubby Area

Answer

Question 3.
What is the highest metric supported in the traditional (not wide metric enabled) reachability TLVs?

a) 127
b) 63
c) 255
d) 1023

Answer

Answers

Question 1.
Which of the following statements are true regarding the ISIS backbone?
(Choose 2)

a) It must be contiguous.
b) It does not need to be contiguous if virtual links are used to connect portioned areas.
c) It consists of all routers, both Level 1/2 and Level-2-only, that have Level 2 adjacencies.
d) It consists of all Level-2-only routers.

Answer
a) It must be contiguous.
c) It consists of all routers, both Level 1/2 and Level-2-only, that have Level 2 adjacencies.

Explanation
The ISIS backbone consists of all routers with Level 2 adjacencies and must be contiguous. ISIS does not provide a mechanism for repairing a partitioned area, whether it is backbone or otherwise.
[4331]

Question 2.
In a pre-RFC 2966 ISIS network, Level 1 areas are most comparable to which of the following OSPF area types?

a) Normal Area
b) Stub Area
c) Not So Stubby Area (NSSA)
d) Totally Stubby Area

Answer
d) Totally Stubby

Explanation
A Level 1 ISIS area receives information about other routers within its area along with a default route toward the backbone. This functionality compares best to the OSPF totally stubby area where LSA types 1 and 2 are permitted within the area, along with the single Type 3 default route toward the backbone.
[4332]

Question 3.
What is the highest metric supported in the traditional (not wide metric enabled) reachability TLVs?

a) 127
b) 63
c) 255
d) 1023

Answer
b) 63

Explanation
The traditional ISIS metric field contains 6 bits for use as a metric and thus allows for a decimal metric of up to a maximum value of 63.
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