Comprehensive and Detailed in-depth Step-by-Step Explanation:
In an Intermediate System to Intermediate System (IS-IS) network, aDesignated Intermediate System (DIS)is elected on broadcast networks to perform the following functions:
Represent the broadcast network as a pseudonode.
Generate and update the Link State Protocol Data Units (LSPs) for the pseudonode.
The DIS is elected based on theDIS priorityvalue, which is configured on IS-IS interfaces. If two routers have the same priority, the router with the higher MAC address becomes the DIS.
Thedefault DIS priorityfor IS-IS interfaces is64, which can be modified depending on the network requirements.
Option A (200):Incorrect. This is not the default value.
Option B (64):Correct. This is the default DIS priority value.
Option C (1):Incorrect. This is not the default value.
Option D (100):Incorrect. This is not the default value.
References:
Huawei HCIA-Datacom Study Guide, Chapter on "IS-IS Basics".
RFC 1195 - Use of OSI IS-IS for Routing in TCP/IP and Dual Environments.