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You have configured RouterA as an IS-IS node with the NET 49.1741.c867.5309.af89.00. Nodes with which of the f

You have configured RouterA as an IS-IS node with the NET 49.1741.c867.5309.af89.00.
Nodes with which of the following NETs would be able to establish an ISIS adjacency with RouterA? (Select 3 choices.)

A. 48.1741.c867.5309.af89.00
B. 49.1741.c867.5309.af89.00

C. 49.1741.3867.5309.af89.00

D. 49.1741.c867.5309.7f89.00

E. 49.1741.c867.6309.af89.00

F. 49.2741.c867.5309.af89.00

Explanation:

Nodes with the following network entity titles (NETs) would be able to establish an IntermediateSystemtoIntermediate System (ISIS) adjacency with RouterA:
– 49.1741.3867.5309.af89.00
– 49.1741.c867.5309.7f89.00
– 49.1741.c867.6309.af89.00

A NET is a hexadecimal address that consists of the following three parts:
– The area ID
– The system ID
– The network service access point (NSAP) selector, or NSEL
The NET has a minimum length of 8 bytes and a maximum length of 20 bytes. Each byte consists of two hexadecimal characters. The NSEL is the last byte in the address and is typically set to 00.

The system ID is always 6 bytes long and precedes the NSEL. Level 1 (L1) routers must have a system ID that is unique within the area, and Level 2 (L2) routers must have a system ID that is unique within the domain. ISIS will not establish an adjacency between two routers with the same system ID.

The area ID is of variable length and precedes the system ID. The first byte, which is part of the area ID, is called the authority and format identifier (AFI) and is typically set to a value of 49 on privately addressednetworks. Routers that share the same area address can form an adjacency.
In this scenario, RouterA is configured with area ID 49.1741, system ID c867.5309.af89, and NSEL 00. Nodes with the following NETs would be able to establish an adjacency with RouterA because their system IDs are different:
– 49.1741.3867.5309.af89.00
– 49.1741.c867.5309.7f89.00
– 49.1741.c867.6309.af89.00

Nodes with the following NETs would not be able to establish an adjacency with RouterA, because their system IDs are the same as RouterA’s system ID:

– 48.1741.c867.5309.af89.00
– 49.1741.c867.5309.af89.00
-49.2741.c867.5309.af89.00

Reference:
https://www.cisco.com/c/en/us/td/docs/ios/12_2/apollo/configuration/guide/fapolo_c/3cfclns.html#wp1012582
https://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfisis.html#wp1018178


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