H12-821_V1.0 Exam Dumps - Huawei HCIP-Datacom Questions and Answers

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of AS_Path Attribute Modification:

The apply as-path command in a route-policy is used to modify the AS_Path attribute of routes. This is often required to influence the selection of routes or to adjust routing policies for incoming or outgoing BGP updates.

2. Parameters of the apply as-path Command:

Option A: Delete

Correct .

The delete parameter removes specific AS numbers from the AS_Path attribute. This is used to simplify or manipulate the AS_Path for specific routing policies.

Option B: Additive

Correct .

The additive parameter appends an AS number to the existing AS_Path attribute, instead of overwriting it. This is useful when you want to prepend AS numbers to influence route selection without removing the original AS_Path.

Option C: Copy

Incorrect .

The copy parameter is not supported in the apply as-path command for modifying AS_Path attributes.

Option D: Overwrite

Correct .

The overwrite parameter replaces the existing AS_Path with a new one. This provides complete control over the AS_Path attribute but removes the original AS_Path entirely.

3. Summary:

The valid parameters for the apply as-path command are delete, additive, and overwrite.

Configuration Analysis:

On R2 , the following configuration has been applied:

acl 200

rule deny source 10.1.0.0 0.0.3.0

rule permit

#

ospf 1

filter-policy 2000 import

This configuration uses ACL 200 to filter routes during import into the OSPF routing table on R2.

Rule deny source 10.1.0.0 0.0.3.0: Blocks routes in the range 10.1.0.0/24 to 10.1.3.0/24 (inclusive).

Rule permit: Allows all other routes to be imported.

Impact of ACL 200 on Route Import:

10.1.0.0/24 to 10.1.3.0/24: These subnets are explicitly denied by ACL 200 and will not appear in R2 ' s routing table.

10.1.4.0/24 and beyond: These subnets are permitted by the rule permit statement and will be imported into R2 ' s routing table.

Routing Table Entries on R2:

Option A (10.1.4.0/24): Exists in R2 ' s routing table because it is permitted.

Option B (10.1.3.0/24): Does not exist because it is denied by ACL 200.

Option C (10.1.2.0/24): Does not exist because it is denied by ACL 200.

Option D (10.1.1.0/24): Does not exist because it is denied by ACL 200.

A (10.1.4.0/24)

In Huawei firewalls, the security level of a zone can be reconfigured by an administrator, making the statement that it cannot be changed false. Other statements accurately describe security level restrictions or defaults ​.

In the provided configuration, IS-IS is enabled on Loopback0 but not on Loopback3 of R2. As a result, R2 will advertise the route 10.0.2.2/32 (from Loopback0 ) to R1 through IS-IS. However, the route 10.0.2.3/32 will not be advertised because IS-IS is not enabled on that loopback interface. The import-route direct command does not override this behavior ​.

When the router ID is configured in both the system view and the BGP view, the router ID in the BGP view takes precedence because BGP-specific configurations override global settings. This ensures that BGP operates with the most relevant configurations ​.

Hello packets are the most basic and essential type of OSPF packets used for the following purposes:

Neighbor discovery – Routers use Hello packets to discover other OSPF routers on the same link.

Neighbor relationship establishment – When two routers exchange matching Hello packets, they move from the " Init " state to " 2-Way " and further into adjacency states.

Neighbor relationship maintenance – Hello packets are sent periodically to ensure that neighbors are still reachable. If Hello packets are missed within the dead interval, the neighbor is considered down.

Neighbor deletion is not a direct function of Hello packets. Neighbor deletion results indirectly from missed Hello packets.

Comprehensive and Detailed in-depth Step-by-Step Explanation:

To answer this question, we need to understand the roles of OSPF routers:

Area Border Router (ABR):

An ABR is a router that connects multiple OSPF areas. It has at least one interface in the backbone area (Area 0) and one or more interfaces in other OSPF areas.

The ABR performs summarization between areas and propagates routing information between them.

Backup Router (BR):

The term " BR " does not exist in OSPF terminology. Instead, OSPF uses the term " Backup Designated Router (BDR). " The BDR is a backup to the Designated Router (DR) in a specific OSPF broadcast or NBMA (Non-Broadcast Multi-Access) network. The BDR takes over the DR ' s responsibilities if the DR fails.

Key Clarification:

An ABR is related to the hierarchical structure of OSPF areas and is not tied to the DR/BDR election process.

A router can function as an ABR without ever being a DR or BDR, as these are separate roles.

Therefore, the statement that an ABR must also be a BR is FALSE.