Free HCIP-Datacom-Core Technology V1.0 Practice Questions

 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 asynchronous mode, BFD control packets are exchanged periodically to detect faults.

 In demand mode, once the session is established, BFD stops sending periodic control packets and relies on external mechanisms to verify connectivity.

 Asynchronous mode is the most commonly used mode. However, the Echo function is supported in asynchronous mode, making Option B incorrect ​.

High-availability Stateful Backup (HSB) ensures synchronization between active and standby devices. If the HSB channel fails to establish, the following causes are possible:

TCP channel not established: The HSB channel relies on a TCP connection. If the TCP session cannot be established, the backup process cannot start.

Mismatched retransmission settings: If the retransmission count and interval for HSB service packets are inconsistent between the two devices, the synchronization process fails.

Incorrect source and destination configurations: If the source IP address and port number on one device do not match the destination IP address and port number on the other, the channel cannot be established.

Option C is incorrect because the priority of the two ACs affects active/standby roles but does not directly impact HSB channel establishment ​.

Comprehensive and Detailed Step-by-Step Explanation:

Routing Table Structure:

Routers maintain a local core routing table and separate protocol routing tables for OSPF, BGP, etc.

The local core routing table stores optimal routes selected based on metrics, protocol preferences, and administrative distances.

Fields in the Core Routing Table:

Destination Address (A): Indicates the destination network or host.

Routing Protocol Preference (B): Determines the priority of routing protocols (e.g., OSPF > RIP).

Routing Protocol (D): Specifies the protocol (e.g., OSPF, BGP) that contributed the route.

Inbound Interface: This is stored in the protocol-specific routing table but not in the local core table.