What are the basic configuration steps to enable IS-IS?

A.
Configure the net system-id command under router isis and enable IS-IS on each
interface with the ip router isis command.

B.
Configure the net system-id and the network net-id commands under router isis.

C.
Configure the network net-id command(s) under router isis and enable IS-IS on each
interface with the ip router isis command.

D.
Configure the network net-id command(s) and the is-type level-1-2 command under router
isis.

E.
Configure the net system-id and the network net-id commands under router isis and
enable IS-IS on each interface with the ip router isis command.

Explanation:
To enable Integrated IS-IS on a router for IP routing is easy. There are many more
commands used to tune the IS-IS processes. However, only the following three commands
are required to start Integrated IS-IS:
• Enable IS-IS as an IP routing protocol, using the command router isis, and assign a
tag if there are multiple IS-IS processes. If the tag is omitted, a tag of zero (0) is assumed.
• Identify the router for IS-IS by assigning a NET to the router with the net command.
• Enable IS-IS on the interfaces participating in IS-IS, using the command ip router isis.
This is slightly different to most other IP routing protocols where the participating interfaces
are specified by network statements. There is no network statement under the IS-IS process.
If there are multiple IS-IS processes, interfaces must state which process they belong to by
specifying the appropriate tag.