H12-821_V1.0 Leak Questions

When the level of an IS-IS interface is changed, the adjacency must be re-established because IS-IS adjacencies are formed based on matching levels (Level-1, Level-2, or both). Other changes, such as cost or hello intervals, do not disrupt the existing adjacency but might impact routing metrics or timing ​.

Comprehensive and Detailed Step-by-Step Explanation:

Definition of the Origin Attribute:

The Origin attribute is a well-known mandatory attribute used to indicate the source of a route. It has three possible values:

i (IGP): The route was injected into BGP using the network command.

e (EGP): The route was learned from an EGP protocol (not commonly used now).

? (Incomplete): The route was redistributed into BGP from another routing protocol.

Analysis of Each Option:

Option A: Correct. When the network command is used, the Origin is set to i (IGP).

Option B: Incorrect. Routes learned from EGP have the Origin attribute set to e (EGP), not ? (Incomplete).

Option C: Correct. BGP prefers routes with the Origin attribute in the order: IGP > EGP > Incomplete.

Option D: Correct. The Origin attribute is a well-known mandatory attribute.

References:

HCIA-Datacom Study Guide, Chapter: BGP Attributes

Huawei BGP Attribute Comparison

 Link fault alarm

 The BFD session goes down.

 Interrupted OSPF neighbor relationship

Intra-area route calculation in OSPF involves only Router LSAs (Type 1) and Network LSAs (Type 2). Summary LSAs (Type 3) are used for inter-area routes and do not participate in intra-area route calculation. Therefore, the statement is false ​.