PDF H12-821_V1.0 Study Guide

 Additional Port Roles in MSTP

Master Port: Indicates the port on the shortest path to the root bridge in a region.

Regional Edge Port: Identifies a port at the boundary of the MST region.

Backup and edge ports exist in RSTP and are not newly introduced by MSTP.

 HCIP-Datacom-Core Reference

MSTP port roles are elaborated in the MSTP configuration sections​​.

 IP Prefix List Matching Conditions

An IP prefix list matches based on:

Mask: Specifies the subnet mask length.

Action: Specifies whether to permit or deny.

Index: Orders the rules within the prefix list.

Port numbers are not applicable as matching conditions in an IP prefix list.

 HCIP-Datacom-Core Reference

IP prefix list configurations are detailed in the routing policy and route filtering chapters​​.

Understanding the Network Setup:

The OSPF network consists of three areas (Area 1, Area 0, and Area 2).

The server's subnet192.168.1.0/24is directly connected to R1 and imported into OSPF using the command:

import-route direct type 1 cost 2

Thetype 1specifies the route as anOSPF Type 1 external route, meaning both the external cost and the internal OSPF cost will be included when calculating the total cost.

The external cost specified for the imported route is2.

Cost Calculation to R2:

The interfaces between the routers are GE interfaces, and the default cost for GE interfaces is1.

The path from R2 to the server goes through the following hops:

R2 → R1:Cost = 1 (intra-area link).

R1 → Server:External cost = 2 (specified in theimport-routecommand).

Total cost to R2:

Intra-area cost (1) + External cost (2) = 3

Verification of Each Option:

Option A (2):Incorrect. This only accounts for the external cost, ignoring the internal OSPF cost.

Option B (4):Incorrect. This overestimates the cost by adding an extra hop.

Option C (3):Correct. The total cost is3(1 for the intra-area link + 2 for the external cost).

Option D (1):Incorrect. This ignores the external cost of the imported route.

Comprehensive and Detailed Step-by-Step Explanation:

DHCP Configuration Issues:

Option C:The DHCP function isdisabled by defaulton Huawei devices. If the administrator forgets to enable it, clients cannot receive IP addresses.

Option D:DHCP uses broadcast messages, which do not traverse routers. If the clients and DHCP server are on different subnets, aDHCP relay agentmust be configured.

Other Options:

Option A:Multiple DHCP servers can coexist as long as their IP address pools do not overlap. This is unlikely to cause the problem.

Option B:STP does not affect DHCP operations unless it delays port activation, which is uncommon in this scenario.