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

Option A is false. When advertising a route to an IBGP peer, the BGP speaker does not modify the AS_Path. It simply advertises the route as-is, preserving the AS_Path learned from EBGP.

Clarification of the options:

B is correct: When a route is sent to an EBGP peer, the local AS is prepended to the AS_Path.

C is correct: The AS_Path begins with the local AS when a new route is advertised to an EBGP neighbor.

D is correct: IBGP does not modify AS_Path when passing routes within the same AS.

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

“BGP speakers prepend their AS number to the AS_Path only when advertising to EBGP peers. IBGP peers do not alter the AS_Path.”

(Chapter: BGP Path Attributes – Section: AS_Path)

Comprehensive and Detailed Step-by-Step Explanation:

BGP Router ID Behavior:

The router ID uniquely identifies a BGP device in the network.

If the router ID is changed, it is equivalent to creating a new BGP instance, and the existing BGP session is reset to establish a new peer relationship.

Impact of Router ID Change:

BGP peering relies on stable identifiers. Changing the router ID disrupts the TCP session and requires reestablishing the relationship.

Comprehensive and Detailed In-Depth Explanation:

Neighbor Discovery Protocol (NDP) replaces ARP in IPv6 and uses ICMPv6 messages for:

Router Solicitation (RS) → Sent by hosts to request Router Advertisement (RA) messages.

Router Advertisement (RA) → Sent by routers to announce prefixes and network parameters.

Neighbor Solicitation (NS) → Used for address resolution and Duplicate Address Detection (DAD).

Neighbor Advertisement (NA) → Sent in response to NS messages.

Redirect → Used by routers to redirect hosts to better gateways.

RS is not directly used for address resolution; Neighbor Solicitation (NS) does this, so the answer should be D.

???? Reference: Huawei HCIA-Datacom Study Guide, NDP and ICMPv6 Packet Types.