H12-821_V1.0 Exam Dumps - HCIP-Datacom-Core Technology V1.0

One multicast MAC address maps to 32 multicast IP addresses due to the limited number of bits used in the mapping process. Specifically, the lower 23 bits of the MAC address map to the lower 23 bits of the multicast IP address, while the high 24 bits of the MAC address are fixed as 0x01005E. Thus, Option B is false ​.

Comprehensive and Detailed in-depth Step-by-Step Explanation:In IS-IS, the interface cost is a metric used to determine the best path to a destination. Lower-cost paths are preferred over higher-cost paths. By default, IS-IS interface costs can range from 1 to 63.

Default Cost Range:

IS-IS allows the configuration of interface costs within the range of 1–63 by default. This range is sufficient for most networks.

Maximum Configurable Cost:

The maximum value that can be configured by default is 63. If there is a requirement for a higher cost range, the metric-style can be changed to wide, which allows the cost range to extend beyond 63.

Option A (67): Incorrect. 67 is not the maximum default value.

Option B (63): Correct. This is the maximum default cost value.

Option C (64): Incorrect. This is beyond the default range.

Option D (68): Incorrect. This is beyond the default range.

References:

Huawei HCIA-Datacom Study Guide, Chapter on "IS-IS Cost and Route Selection".

RFC 5308 – Routing IPv6 with IS-IS.

When OSPF routers exchange LSDBs using Database Description (DD) packets, they first establish a master-slave relationship. The router with the larger Router ID becomes the master, setting the MS (Master/Slave) bit in the DD packets. This hierarchical relationship ensures an orderly exchange of routing information ​.

Comprehensive and Detailed In-Depth Explanation:

IP Multicast vs. Broadcast:

A. TRUE → Unlike broadcast, which sends data to all hosts in a subnet, multicast only sends data to interested receivers, preventing flooding.

B. TRUE → Multicast optimizes bandwidth usage by sending a single copy of data, which is then replicated at network routers only when necessary.

IP Multicast vs. Unicast:

C. FALSE → Multicast does not improve security; it may expose data to unintended receivers if not properly controlled.

D. FALSE → Multicast reduces the load on the source because a single data stream serves multiple receivers instead of sending individual unicast streams.

📖 Reference: Huawei HCIA-Datacom Study Guide, IP Multicast Principles and Benefits.

ï‚· ACL Number Ranges

Basic ACLs: Numbered from 2000 to 2999.

Advanced ACLs: Numbered from 3000 to 3999.

Layer 2 ACLs: Numbered from 5000 to 5999.

User-defined ACLs: Numbered from 4000 to 4999.

ï‚· HCIP-Datacom-Core Reference

ACL classifications and their number ranges are covered in the ACL principles and configuration chapters​​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of BFD Optimization:

BFD (Bidirectional Forwarding Detection) is a protocol that provides rapid detection of link failures.

Optimizing BFD involves adjusting parameters to balance between detection speed and network stability.

2. Analysis of Each Statement:

Option A: After a high priority is configured for BFD packets, BFD packets are preferentially forwarded.

Correct (True Statement).

High priority ensures that BFD packets are not delayed or dropped under congestion, improving detection accuracy.

Option B: To quickly learn about the network status and performance requirements, you can set the interval for sending BFD packets to the minimum value.

Incorrect (False Statement).

Setting the interval to the minimum value can lead to excessive BFD session flapping, which may overload the network or cause instability. The interval should be configured based on network requirements and conditions, rather than set to the minimum.

Option C: On a live network, some devices switch traffic only when a BFD session changes to the Up state... configure a delay to compensate for the time difference.

Correct (True Statement).

This is a valid optimization to avoid issues caused by timing mismatches between BFD and routing protocols.

Option D: If a BFD session flaps, master/backup switchovers are frequently performed... set the WTR time.

Correct (True Statement).

The WTR (Wait to Restore) timer helps stabilize BFD by delaying session recovery after a flap, reducing the risk of frequent switchovers.

3. Summary:

The false statement is B, as setting the BFD packet interval to the minimum can destabilize the network.

Routing policies are used to control how routes are imported, advertised, or received. Policy-Based Routing (PBR) is used to forward packets based on policies, bypassing the routing table. Routing policies are not used for packet forwarding ​.

In RSTP, a port in the discarding state neither forwards data frames nor learns MAC addresses. A port in the learning state does not forward data frames but starts learning MAC addresses. Therefore, options A and B are correct, while C and D are incorrect due to misunderstandings of these states ​.