Exam H12-831_V1.0 Topic 1 Question 7 Discussion

Comprehensive and Detailed In-Depth Explanation:
1. Understanding the DIS (Designated Intermediate System) in IS-IS
* In IS-IS, the DIS (Designated Intermediate System) is similar to the DR (Designated Router) in OSPF.
* Unlike OSPF, IS-IS does not use an election based on priority; instead, the router with the highest priority becomes the DIS.
* If there is a tie in priority, the router with the highest MAC address on the interface becomes the DIS.
* The DIS is responsible for generating additional LSPs (pseudonode LSPs) for the link and synchronizing the database between routers.
2. How to Identify If the Router Is the DIS from the LSP
* In the given LSP output, there are NO pseudonode LSPs (LSPs ending with .01).
* The DIS is responsible for creating pseudonode LSPs, which represent a multi-access network in the IS-IS topology.
* If the router were the DIS, it would generate both its own LSP (ending in .00) and a pseudonode LSP (ending in .01).
* Since we only see an LSP ending in .00, this confirms that the router is NOT the DIS.
3. Evaluating the Answer Choices
* Option A (TRUE) - Correct:
* Since no pseudonode LSP is present, the router is not the DIS.
* This confirms that the statement is TRUE.
* Option B (FALSE) - Incorrect:
* If the router were the DIS, it would generate pseudonode LSPs, but they are missing from the output.
* Therefore, the statement is NOT false.
Final Answer:
HCIP-Datacom-Advanced Routing & Switching Technology References:
* IS-IS Designated Intermediate System (DIS) Selection Process
* Pseudonode LSP Generation in Multi-Access Networks
* IS-IS LSP Structure and Identification of DIS