Which two prerequisites does IS-IS need to operate? (Choose two.)

A.
IS-IS must be able to communicate between devices using IP.

B.
IS-IS must be able to communicate using CLNS.

C.
IS-IS must have a valid IP address configured on the loopback.

D.
IS-IS must have a valid CLNS address.

Explanation:
Integrated IS-IS, also known as Dual IS-IS, was to provide a single routing protocol with the capabilities of routing both Connectionless Network Service (CLNS) and IP

NSAPs (Network Service Access Points) and Addressing

* NSAP is the network layer address for CLNS (Connectionless Network Service) packets
* An NSAP consists of 3 parts, area address, system ID, and n-selector
* All routers in an area must use the same area address
* Each node in an area must have a unique systemID
* All L2 routers in a domain must each have a unique systemID
* Area address is like OSPF area number
* System ID is like an OSPF router ID