Question 1.
What is the function of the NSAP Selector in OSI-based addressing?
(Choose 2)

a) To differentiate between multiple addresses configured on the same node
b) To direct PDUs to corresponding upper-layer processes within a node
c) To signify a particular interface as the Designate Router for a segment
d) To differentiate between multiple addresses configured within an area

Answer

Question 2.
The Area ID used in the NSAP address can be what length?

a) Between six and ten bytes
b) Between one and six bytes
c) Between two and eight bytes
d) Between one and thirteen bytes

Answer

Question 3.
Where is the backbone in an ISIS multi-area network?

a) The set of routers with interfaces in area 0
b) The set of Level Two only routers
c) The set of Level Two and Level One/Two routers
d) The set of all routers with Level Two interfaces in area 0

Answer

Answers

Question 1.
What is the function of the NSAP Selector in OSI-based addressing?
(Choose 2)

a) To differentiate between multiple addresses configured on the same node
b) To direct PDUs to corresponding upper-layer processes within a node
c) To signify a particular interface as the Designate Router for a segment
d) TO differentiate between multiple addresses configured within an area

Answer
a) To differentiate between multiple addresses configured on the same node
b) To direct PDUs to corresponding upper-layer processes within a node

Explanation
The NSAP Selector is used in OSI-based addressing to allow multiple CLSP processes to exist on the same node. Each process can utilize a unique address by altering the value of this last byte of the address. Remember that, for ISIS, the NSAP Selector must always be 0.
[3926]

Question 2.
The Area ID used in the NSAP address can be what length?

a) Between six and ten bytes
b) Between one and six bytes
c) Between two and eight bytes
d) Between one and thirteen bytes

Answer
d) Between one and thirteen bytes

Explanation
The full range of NSAP addresses is rarely used except in ATM addressing.

For ISIS, in general an Area ID can be as few as one byte and as many as thirteen.
[3927]

Question 3.
Where is the backbone in an ISIS multi-area network?

a) The set of routers with interfaces in area 0
b) The set of Level Two only routers
c) The set of Level Two and Level One/Two routers
d) The set of all routers with Level Two interfaces in area 0

Answer
c) The set of Level Two and Level One/Two routers

Explanation
The backbone of an ISIS network comprises the set of all routers with L2 capabilities. This set of routers may indeed possess numerous area addresses, and, in fact, no particular significance is given to any unique area value, including area 0.
[3928]