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Stateless Address Autoconfiguration (SLAAC)is an IPv6 mechanism where a host automatically configures its ownglobal unicast addresswithout requiring a DHCPv6 server.

IPv6 Address Format in SLAAC:

First 64 bits→Network Prefix(received from the router's RA message).

Last 64 bits→Interface Identifier(generated using EUI-64 or a randomly assigned value).

Why is the Prefix Always 64 Bits?

SLAAC requires a/64 prefixbecause the host needsthe lower 64 bitsto generate a unique address.

IPv6 Neighbor Discovery (ND) and Address Autoconfiguration are designed for a /64 subnet mask.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IPv6 Configuration Guide – SLAAC Addressing and Prefix Allocation

HCIE-Datacom Training Material – IPv6 Stateless Address Autoconfiguration (SLAAC)

Error analysis:

The error SSLError and CertificateError indicates the server's SSL certificate'shostname doesn't match the IP addressbeing used in the request.

This happens when acertificate is issued for a domain (like devzone.huawei.com), but the client accesses it via an IP address (139.9.213.72), causing atrust failure.

Correct statements:

A—✅: The client doesn't trust the SSL certificate → correct.

B—✅: SSL verification fails due to hostname mismatch.

C—✅: Disabling verification with verify=False bypasses the check (only recommended in lab/testing environments).

D—❌: Uses http instead of https, which changes protocol and defeats the purpose of SSL. Also uses POST without API path.

Correct answers: A, B, C

There arethree standard inter-AS MPLS VPN options, as per RFC 4364:

Option A (Back-to-Back VRF):

VRFs are directly connected between ASBRs using routing exchange (like static/BGP).

No label switching between ASs —no MPLS label neededbetween ASs.

Option B (EBGP Label Exchange):

ASBRs exchange labeled VPNv4 routes via EBGP.

One MPLS label is required —MPLS forwarding across AS boundaryis used.

Option C (End-to-End LSP):

Full end-to-end LSP is created across ASs.

MPLS labels are definitely usedend-to-end, even between ASs.

Option D (Commonly vendor-specific extensions based on Option B/C):

Similar to Option C —requires MPLS labels.

So:

B. Option B— needs MPLS label✅

D. Option D— also needs MPLS label✅

A. Option A—no MPLS label❌

C. Option C— also uses MPLS label✅, but not listed as an answer option in this question format (should have been).

Assuming valid options areA, B, D, the correct ones needing MPLS labels are:

Correct answers: B, D

When Spanning Tree Protocol (STP) is not enabled on a network, loops can occur in Layer 2 Ethernet networks, leading to various network issues. STP is designed to prevent loops by blocking redundant paths, and its absence can cause broadcast storms, MAC address table instability, and resource exhaustion. Let’s analyze each option in the context of Huawei HCIE Datacom documentation and network behavior:

A. A loop alarm is generated on the LAN switch.

This option is incorrect. Huawei switches, as per HCIE Datacom standards, do not automatically generate a specific "loop alarm" unless configured with loop detection features (e.g., Huawei’s Loop Detection Protocol or similar mechanisms). Without STP or loop detection enabled, the switch may not explicitly generate an alarm for a loop; instead, it will exhibit symptoms like broadcast storms or flapping MAC entries. Therefore, this is not a direct symptom of an STP-less loop. Reference: Huawei HCIE Datacom V3.0 Training Materials, Section 4.2 – Spanning Tree Protocol and Loop Prevention.

B. CPU usage is too high.

This option is correct. When a loop occurs without STP, broadcast packets (and sometimes multicast or unknown unicast packets) circulate endlessly in the network. This leads to excessive processing by switches as they handle these packets, resulting in high CPU usage. Huawei switches, as described in HCIE Datacom documentation, can experience CPU overload due to continuous packet forwarding and processing in a looped environment. Reference: Huawei HCIE Datacom V3.0, Chapter 5 – Switch Performance and Loop Management.

C. MAC entries flap.

This option is correct. In a loop without STP, switches continuously receive frames from multiple ports, causing MAC address tables to update repeatedly as the same MAC address appears on different ports. This "flapping" of MAC entries destabilizes the network and can lead to incorrect frame forwarding. Huawei HCIE Datacom emphasizes MAC address table stability as a critical aspect affected by loops, as outlined in Section 4.3 – Ethernet Switching and Loop Mitigation. Reference: Huawei HCIE Datacom V3.0, Section 4.3.

D. Host receives a large number of broadcast packets.

This option is correct. A loop without STP causes broadcast packets to circulate indefinitely, creating a broadcast storm. Hosts connected to the network will receive an overwhelming number of these packets, potentially leading to performance degradation or even network timeouts. This is a well-documented symptom in Huawei HCIE Datacom training, specifically in discussions about loop prevention mechanisms. Reference: Huawei HCIE Datacom V3.0, Chapter 4 – Layer 2 Loop Prevention.

Thus, the correct symptoms of a loop occurring due to the absence of STP include high CPU usage, flapping MAC entries, and hosts receiving a large number of broadcast packets. Option A is incorrect as it requires specific loop detection configuration, which is not implied in the question.