Huawei H12-821_V1.0 - HCIP-Datacom-Core Technology V1.0

Comprehensive and Detailed Step-by-Step Explanation:

1. What is a Firewall Session?

A firewall session is an entry used to maintain the connection state of a protocol.

When a packet is forwarded, the firewall creates a session for it and tracks subsequent packets for the same connection to ensure efficient forwarding and security enforcement.

2. Analysis of Each Option:

Option A: Subsequent fragment

Incorrect.

A session is created for the initial fragment of a packet. Subsequent fragments are matched to the existing session and do not trigger the creation of a new session.

Option B: ICMP error packet

Incorrect.

ICMP error packets (e.g., Destination Unreachable) are considered exceptions and do not create new sessions.

Option C: GRE (Generic Routing Encapsulation)

Correct.

GRE is a tunneling protocol that encapsulates packets. A firewall creates a session for GRE traffic to track the state of the encapsulated connection.

Option D: TCP (Transmission Control Protocol)

Correct.

TCP is a connection-oriented protocol, and firewalls create sessions for TCP connections to track their state (e.g., SYN, SYN-ACK, FIN).

3. Summary:

The firewall creates sessions forGREandTCPprotocols.

OptionA is false. When advertising a route to an IBGP peer, theBGP speaker does not modifythe AS_Path. It simply advertises the routeas-is, preserving the AS_Path learned from EBGP.

Clarification of the options:

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

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

Dis correct: IBGP doesnotmodify 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)

AI-driven networks focus on maximizing efficiency by minimizing latency to enhance data processing and decision-making speed. The AI era emphasizes leveraging large data volumes and ensuring rapid data center interconnectivity. This makes low latency a critical requirement for AI-ready data center networks, as highlighted in Huawei's AI and data center network optimization materials ​.

ï‚· OSPF Authentication Overview

OSPF supports three authentication modes:

Null Authentication: No authentication (default).

Plaintext Authentication: Uses clear-text passwords.

MD5 Authentication: Secure cryptographic authentication.

ï‚· Interface-Level Priority

When both interface-level and area-level authentication are configured, OSPF prioritizesinterface-level authentication. This ensures that interface-specific security overrides area-wide configurations for greater granularity and security.

ï‚· HCIP-Datacom-Core Reference

OSPF authentication hierarchy and configurations are detailed in the OSPF security configuration chapter​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is First-Time Authentication in SSH?

When an SSH client connects to an SSH server for the first time, the server's public key is not yet known to the client.

Enabling first-time authentication allows the SSH client to accept the server's public key and save it for future connections. This feature eliminates the need for manual configuration of the server's public key on the client.

2. Process Explanation:

The SSH client connects to the server and receives the server's public key.

The client accepts the key and saves it in its local key database (e.g., known_hosts file).

For subsequent connections, the client uses the saved public key to authenticate the server.

3. Why the Statement is TRUE:

First-time authentication simplifies SSH setup and is a commonly used method when connecting to new servers. It ensures that future connections are authenticated using the saved public key.

Comprehensive and Detailed Step-by-Step Explanation:

IS-IS Area Division:

IS-IS divides areas byrouters, not by links. A router is assigned to a specific IS-IS area, but it can belong to multiple levels:

Level 1:Maintains the LSDB (Link State Database) for the local area only.

Level 2:Maintains the LSDB for the backbone area and exchanges routes between areas.

Behavior of a Level 1-2 Router:

A router configured as Level 1-2 must maintain two separate LSDBs:

One for intra-area routes (Level 1).

One for inter-area routes (Level 2).

Incorrect Statement:

The statement that an IS-IS router only needs to maintain the LSDB of its area is incorrect because Level 1-2 routers maintain LSDBs for both levels.

Comprehensive and Detailed In-Depth Explanation:

ANET (Network Entity Title)consists of three parts:

Area Address→ Identifies the IS-IS area.

System ID→ Uniquely identifies the router.

SEL (NSEL - N-selector)→ Always0in IS-IS.

TheArea Addresspart contains:

AFI (Authority and Format Identifier)→ Identifies the address type.

IDI (Initial Domain Identifier)→ Identifies the routing domain.

System ID is NOT part of the Area Address, so the correct answers areB (AFI) and C (IDI).

📖Reference:Huawei HCIA-Datacom Study Guide, IS-IS Addressing and NET Structure.

RPF (Reverse Path Forwarding) checks are used to prevent multicast loops. An RPF check uses theunicast routing table(ormulticast static routes, if configured) to determine the correct incoming interface for a multicast packet.

Multicast protocols like PIM use the RPF mechanism, and the unicast routing table is the primary reference.

Multicast dynamic routing protocolsdo not maintain their own separate tablesfor RPF by default.

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

“RPF checks are performed using the unicast routing table or multicast static routes. The interface through which the multicast source is reachable is considered valid for RPF.”

(Chapter: Multicast – Section: RPF Principle)

Comprehensive and Detailed In-Depth Explanation:

A. TRUE→ The interfaceGigabitEthernet0/0/1has anIP address of 192.168.1.1.

B. TRUE→ TheIGMP version is explicitly stated as IGMPv2.

C. TRUE→ Themaximum query response timefor IGMPis set to 10 seconds.

D. TRUE→ TheIGMP Query Interval is configured as 60 seconds, meaning the routersends Group-Specific Queries every 60 seconds.

📖Reference:Huawei HCIA-Datacom Study Guide, IGMP Configuration and Query Timers.