300-420 · Question #35
When a network is designed using IS-IS protocol, which two circuit types are supported? (Choose two.)
The correct answer is B. multiaccess E. point-to-point. IS-IS natively defines exactly two circuit (interface) types. Multiaccess / broadcast (B): used on shared media such as Ethernet, where IS-IS elects a Designated Intermediate System (DIS) to manage adjacencies and generate a pseudonode LSP representing the LAN. Point-to-point…
Question
When a network is designed using IS-IS protocol, which two circuit types are supported? (Choose two.)
Options
- Anonbroadcast multiaccess
- Bmultiaccess
- Cpoint-to-multipoint
- Dnonbroadcast
- Epoint-to-point
How the community answered
(58 responses)- A2% (1)
- B91% (53)
- C5% (3)
- D2% (1)
Explanation
IS-IS natively defines exactly two circuit (interface) types. Multiaccess / broadcast (B): used on shared media such as Ethernet, where IS-IS elects a Designated Intermediate System (DIS) to manage adjacencies and generate a pseudonode LSP representing the LAN. Point-to-point (E): used on serial links or explicitly configured on Ethernet interfaces; two routers form a single adjacency directly without a DIS election. IS-IS does not have a built-in NBMA (nonbroadcast multiaccess) circuit type (A, D) like OSPF does - NBMA environments are handled by configuring IS-IS interfaces as point-to-point subinterfaces. IS-IS also does not support a point-to-multipoint (C) circuit type natively. These two circuit types cover all IS-IS deployment scenarios.
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