Huawei Updated H12-821_V1.0 Exam Questions and Answers by adele

Route summarization in OSPF is restricted to specific routers: Area Border Routers (ABRs) and Autonomous System Boundary Routers (ASBRs). These devices perform summarization to reduce routing table size and minimize advertised routing information between areas or across AS boundaries. Regular routers cannot perform route summarization, making this statement false ​.

 R3, as the DIS in the Level-2 domain, periodically sends Complete Sequence Number Protocol Data Units (CSNPs) to ensure LSDB synchronization among Level-2 routers.

 R1 and R2 are in a Level-1 domain, and IS-IS requires the receiving router (R2) to acknowledge an LSP from R1 by sending a Partial Sequence Number Protocol Data Unit (PSNP).

 IS-IS LSPs in a broadcast network are sent using multicast, not unicast, making option C incorrect.

 For Level-2 LSPs, acknowledgments are not provided using PSNP by R3; CSNPs are sufficient for synchronization ​.

In OSPF (Open Shortest Path First), each router maintains aLink-State Database (LSDB), which must be synchronized with other routers in the same area. When an OSPF router receives anLSA (Link-State Advertisement)that it doesnot already have in its LSDB, it takes the following steps:

It updates its LSDB with the new LSA.

It floods the LSA to all its other OSPF neighbors (except the one from which it received the LSA).

This ensures that all routers in the OSPF area eventually converge to the same network topology.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“When an LSA is received and it is newer or not present in the LSDB, the router updates the LSDB and floods the LSA to other neighbors to ensure database synchronization.”

(Chapter: OSPF Fundamentals – Section: LSDB Synchronization)

In the PIM protocol,Register StopandGraftmessages are sent with unicast destination addresses, typically to specific neighbors or RP (Rendezvous Point) routers. Other messages likeBootstrapandAssertuse multicast addresses for broader dissemination across the network ​.