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

Comprehensive and Detailed In-Depth Explanation:

STP Port Roles :

Root Port (RP) → Connects directly to the Root Bridge .

Designated Port (DP) → Forwards traffic for a given segment.

RSTP introduces two additional roles to improve redundancy:

Backup Port → A redundant Designated Port (on the same switch).

Alternate Port → A backup Root Port (path to the Root Bridge).

All four roles exist in RSTP , making the correct answer A, B, C, D .

???? Reference: Huawei HCIA-Datacom Study Guide, RSTP Port Roles and Rapid Convergence.

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding the Prefix List Configuration:

The command ip ip-prefix test index 10 permit 10.0.0.0 8 less-equal 32 defines the following:

The prefix base is 10.0.0.0 with a mask length of 8 bits.

The less-equal 32 condition allows routes with mask lengths ranging from 8 to 32 bits to match.

2. Analysis of Each Route:

Option A: 10.1.1.1/32

Correct .

The prefix 10.1.1.1/32 falls within the 10.0.0.0/8 network range and has a mask length of 32 bits, which satisfies the less-equal 32 condition.

Option B: 10.1.1.0/6

Incorrect .

The prefix 10.1.1.0/6 has a mask length of 6 bits, which is shorter than the base prefix length of 8. It does not satisfy the condition.

Option C: 10.1.1.0/24

Correct .

The prefix 10.1.1.0/24 falls within the 10.0.0.0/8 network range and has a mask length of 24 bits, which satisfies the less-equal 32 condition.

Option D: 10.0.0.0/16

Correct .

The prefix 10.0.0.0/16 falls within the 10.0.0.0/8 network range and has a mask length of 16 bits, which satisfies the less-equal 32 condition.

3. Summary:

The prefixes that match the configuration are 10.1.1.1/32, 10.1.1.0/24, and 10.0.0.0/16.

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.