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

The filter-policy command in IS-IS is used to control the advertisement and filtering of routing information. However, it does not directly filter LSPs (Link State Packets); instead, it controls route advertisements. The false statement here is that it filters LSPs ​.

Comprehensive and Detailed Step-by-Step Explanation:

ACL Capabilities:

ACLs are versatile tools that can match:

Data packets: Using IP addresses, protocols, ports, etc.

Routes: ACLs can be used in route filtering, matching both IP prefix length and mask length.

Correct Statement:

ACLs can match both the IP address prefix length and mask length in route filtering applications.

Comprehensive and Detailed In-Depth Explanation:

Type 7 LSAs (NSSA External LSAs) are used in Not-So-Stubby Areas (NSSAs) to carry external routing information.

These LSAs are generated only by ASBRs within an NSSA , and later converted to Type 5 LSAs by the ABR .

Stub areas do not allow ASBRs , meaning Type 7 LSAs cannot exist in a stub area .

The question incorrectly states that Type 7 LSAs can be generated in stub areas , which is false .

???? Reference: Huawei HCIA-Datacom Study Guide, OSPF LSA Types and Area Configurations.

Internet – This community attribute allows a route to be advertised to any BGP peer , including EBGP and IBGP. This is the default behavior if no other restrictive community is attached.

No_Advertise – Prevents the route from being advertised to any peer.

No_Export – Prevents the route from being advertised to EBGP peers .

No_Export_Subconfed – Restricts the route from being advertised outside the sub-AS in a confederation.

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

“The Internet community attribute allows unrestricted advertisement of a route. Other community attributes like No_Advertise and No_Export limit route propagation.”

(Chapter: BGP Community Attributes – Section: Well-known Communities)

Comprehensive and Detailed In-Depth Explanation:

When a packet is checked against an Access Control List (ACL) , it is processed based on rule matches.

" Unmatched " scenarios occur if:

A. TRUE → The packet does not match any ACL rule .

C. TRUE → No ACL is configured , so there are no rules to match.

D. TRUE → An empty ACL exists , meaning no rules are defined.

B is incorrect because if the packet matches a deny rule, it is " matched " and explicitly dropped , not " unmatched " .

???? Reference: Huawei HCIA-Datacom Study Guide, ACL Rule Matching and Processing Logic.

 Notification Message Purpose

BGP Notification messages are used to report errors or terminate a connection. They do not request peers to resend routing information after routing policies are changed.

Routing updates following policy changes require manual resynchronization, not Notification messages.

 HCIP-Datacom-Core Reference

The purpose and usage of Notification messages are discussed in the BGP operation chapters​​.

OSPF supports both area-level and interface-level authentication. When both are configured, interface authentication takes precedence over area authentication. This hierarchy ensures that specific interface-level configurations override the broader area-level settings when applicable ​.

Comprehensive and Detailed In-Depth Explanation:

Source-Specific Multicast (SSM) uses (S, G) addressing instead of the traditional (*, G) used in Any-Source Multicast (ASM) .

IGMP SSM Mapping is used to enable IGMPv1 and IGMPv2 hosts (which do not support explicit source selection) to work in an SSM environment by mapping (*, G) to (S, G) .

A. TRUE → The mapping allows IGMPv1/v2 to function in an SSM network .

B. TRUE → IGMPv3 natively supports SSM , so SSM mapping is not needed for IGMPv3 .

C. FALSE → The SSM address range is 232.0.0.0/8 in IPv4 , but this is not the only range used for SSM globally .

D. TRUE → If IGMP SSM mapping is disabled, IGMPv1/v2 cannot work in an SSM network because they do not support explicit source selection .

???? Reference: Huawei HCIA-Datacom Study Guide, IGMP Versions and SSM Mapping.

 BGP Route Flapping and Mitigation

While route flapping is a concern in large-scale networks, BGP employs mechanisms such as Route Dampening to mitigate its impact. Route dampening suppresses frequently flapping routes for a period of time to reduce resource consumption and network instability.

Therefore, it is incorrect to state that the issue cannot be resolved in BGP.

 HCIP-Datacom-Core Reference

The mechanism of route dampening is detailed in the BGP optimization chapters​​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is GRE (Generic Routing Encapsulation)?

GRE is a tunneling protocol that allows the encapsulation of various types of packets (e.g., IPv4, IPv6, multicast, etc.) to be transmitted over another protocol (e.g., IP).

GRE is used to create point-to-point connections over heterogeneous networks.

2. Analysis of Each Option:

Option A: GRE is a Layer 2 VPN encapsulation technology.

Incorrect.

GRE operates at Layer 3 (Network Layer) and encapsulates Layer 3 packets. It is not a Layer 2 VPN encapsulation technology like MPLS or Ethernet-over-IP.

Option B: GRE enables encapsulated data packets to be transmitted over another network layer protocol, but cannot encapsulate multicast data.

Incorrect.

GRE supports the encapsulation and transmission of multicast data packets. This is one of its key features, making it suitable for protocols like OSPF and multicast applications.

Option C: GRE tunnels can work with IPsec to ensure the security of multicast services such as voice and video.

Correct.

GRE by itself does not provide encryption or security. However, GRE can work with IPsec to secure the encapsulated traffic, including multicast data, for services like voice and video.

Option D: GRE tunnels can extend the working range of network protocols with hop limits.

Correct.

GRE encapsulates packets, effectively resetting their hop limits and allowing protocols with limited hop counts (e.g., RIP) to work over larger networks.

3. Summary:

The correct options are C and D .