Pass the Huawei HCIP-Datacom H12-821_V1.0 Questions and answers with CertsForce

TheDHCPNAKmessage is sent by the DHCP server to the client to indicate that the requested configuration is not valid. Messages likeDHCPDiscover,DHCPRequest, andDHCPReleaseare initiated by the client in the DHCP process ​.

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

 Indemand 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 ​.

Policy-Based Routing (PBR) on interfaces is used to forward traffic based on specific policies rather than the routing table. However, PBR is not suitable for modifying the next-hop of locally originated traffic. Other scenarios listed are typical use cases for interface PBR ​.

The question indicates that a router performs a lookup in its FIB table for a packet and determines that the tunnel ID in the matching entry is 0, suggesting that the packet needs to be forwarded through a tunnel such as an MPLS tunnel. However, this is a misunderstanding of the FIB functionality.

FIB Table OverviewThe Forwarding Information Base (FIB) is used to make packet-forwarding decisions. Entries in the FIB include next-hop information, which can be directly linked to an interface or a tunnel.

If theTunnel IDis0, it indicates that the packet is forwarded via a normal routing path and not through a tunnel.

For MPLS or other tunnels, the Tunnel ID would have a non-zero value pointing to the associated tunnel.

MPLS Tunnel OperationWhen a router forwards packets through an MPLS tunnel, a label-switched path (LSP) is set up. The FIB would reflect specific tunnel identifiers for packets that need such encapsulation.

HCIP-Datacom-Core Reference

Routing Principles and MPLS​explain the forwarding mechanisms clearly, stating that if a packet is routed normally, the tunnel ID remains0.

The section on MPLS​clarifies the encapsulation process and the role of tunnel identifiers.

Hence, the claim in the question is incorrect. A Tunnel ID of0implies no tunneling is required, and normal IP forwarding occurs

Comprehensive and Detailed In-Depth Explanation:

A. TRUE→ Ifpreemption is enabled, ahigher-priority routercan take over as theMaster.

B. TRUE→ Ifpreemption is disabled, thecurrent Master remains activeeven if a higher-priority router joins.

C. TRUE→ TheMaster router sends VRRP Advertisement packetsto maintain its role.

D. FALSE→ If aVRRP router is the IP address owner, itautomatically becomes the Masterwithout needing toparticipate in an election.

????Reference:Huawei HCIA-Datacom Study Guide, VRRP Priority and Preemption Mechanisms.

 IPv6 Address Behavior

Manually configured link-local addressesdo not have a higher prioritythan automatically generated ones; they coexist and are equally preferred for local communication.

The other statements are true:

A.Link-local addresses can use the EUI-64 method for quick generation.

B.Anycast addresses are only used as destination addresses.

C.An interface can have multiple global unicast addresses with different prefixes.

 HCIP-Datacom-Core Reference

IPv6 address types and priority behaviors are detailed in the IPv6 addressing sections​​.

Comprehensive and Detailed Step-by-Step Explanation:

BGP Route Filtering:

BGP provides flexible policies for route filtering to optimize routing table size and reduce network resource usage.

By configuringroute filters, a device can advertise only required routes to peers, thereby improving efficiency.

Purpose of Filtering:

Reduces the routing table size.

Decreases CPU and memory usage on routers.

Limits unnecessary route propagation.

Comprehensive and Detailed Step-by-Step Explanation:

Switch Stack Overview:

In a switch stack, roles are assigned asmaster,standby, andslave.

The master handles configuration and control, while the standby serves as the backup master.

Behavior During Master Restart:

D:If the master switch restarts, the standby switch immediately takes over as the new master.

B:After the original master switch restarts, it becomes the master again (default behavior).

Incorrect Options:

A:The slave switch is not promoted to standby before the master switch restart completes.

C:The original standby switch remains the master after the restart.

In IS-IS:

Level-1 routerscan only form neighbor relationships with other Level-1 routersin the same area.

Level-2 routerscan form neighbor relationships with other Level-2 routersregardless of area ID.

Level-1-2 routerscan form relationships at both levels depending on the peer's configuration.

So, iftwo Level-1 routershavedifferent area addresses, theycannotestablish a neighbor relationship.

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

“Level-1 routers must have the same area address to establish neighbor relationships. Level-2 routers can peer across different areas.”

(Chapter: IS-IS Protocol Principles – Section: Neighbor Establishment)

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 ​.