Which statement is true about enabling IS-IS routing and using the net command to configure the
NSAP address?

A.
NSAP addresses have a fixed size of 20 bytes.

B.
The NSEL must always be 00 to identify the router.

C.
The area address follows the system ID field before the NSEL field.

D.
An AFI of 39 indicates that the AFI is a locally administered private address.

Explanation:
http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a00800a3e6f.shtml