Free Huawei H12-821_V1.0 Practice Exam with Questions & Answers | Set: 8

Network Types and Corresponding Link Layer Protocols

Broadcast: Ethernet

Point-to-Point (P2P): PPP, HDLC

Point-to-Multipoint (P2MP): PPP

Non-Broadcast Multi-Access (NBMA): Frame Relay

 OSPF Network Types:

OSPF classifies networks based on link layer protocols into the following types:

Broadcast: This type assumes that all routers on the network can communicate directly with one another using multicast or broadcast frames. Ethernet networks are typical examples.

Point-to-Point (P2P): This type is used for links that connect two routers directly. Common protocols include PPP (Point-to-Point Protocol) and HDLC.

Point-to-Multipoint (P2MP): This type simulates multiple point-to-point connections over a single physical network, often used in WAN scenarios where PPP is employed.

Non-Broadcast Multi-Access (NBMA): These networks connect multiple devices but lack native broadcast capability, such as Frame Relay.

Comprehensive and Detailed Step-by-Step Explanation:

IGMPv1 Querier Selection:

In IGMPv1, there is no built-in querier election mechanism. Querier selection depends on the multicast routing protocol (e.g., PIM).

IGMPv2 and IGMPv3 Querier Selection:

In IGMPv2 and IGMPv3, the router interface with thelargest IP addressin the multicast group is selected as the querier.

Correct Statement:

The statement accurately describes the querier selection mechanisms in IGMP versions.

Comprehensive and Detailed Step-by-Step Explanation:

Routing Table Structure:

Routers maintain a localcore routing tableand separateprotocol routing tablesfor OSPF, BGP, etc.

The local core routing table storesoptimal routesselected based on metrics, protocol preferences, and administrative distances.

Fields in the Core Routing Table:

Destination Address (A):Indicates the destination network or host.

Routing Protocol Preference (B):Determines the priority of routing protocols (e.g., OSPF > RIP).

Routing Protocol (D):Specifies the protocol (e.g., OSPF, BGP) that contributed the route.

Inbound Interface:This is stored in the protocol-specific routing table but not in the local core table.

High-availability Stateful Backup (HSB) ensures synchronization between active and standby devices. If the HSB channel fails to establish, the following causes are possible:

TCP channel not established: The HSB channel relies on a TCP connection. If the TCP session cannot be established, the backup process cannot start.

Mismatched retransmission settings: If the retransmission count and interval for HSB service packets are inconsistent between the two devices, the synchronization process fails.

Incorrect source and destination configurations: If the source IP address and port number on one device do not match the destination IP address and port number on the other, the channel cannot be established.

Option C is incorrect because the priority of the two ACs affects active/standby roles but does not directly impact HSB channel establishment ​.

Understanding DHCPv6:

DHCPv6 (Dynamic Host Configuration Protocol for IPv6) is used to assign configuration parameters to IPv6 clients.

It supports bothstatefulandstatelessmodes:

Stateful: Assigns IPv6 addresses and other configuration parameters.

Stateless: Assigns only configuration parameters (e.g., DNS server) without providing IPv6 addresses.

HCIP-Datacom-Core Technology Training Material (IPv6 Address Configuration and DHCPv6)​​.

Analysis of Parameters:

A. Gateway address:

False. DHCPv6 does not assign the default gateway. Instead, the default gateway is advertised by routers usingRouter Advertisement (RA)messages in IPv6.

B. DNS server address:

True. DHCPv6 can assign the IPv6 address of DNS servers to the client.

C. IPv6 address/prefix:

True. In stateful mode, DHCPv6 assigns IPv6 addresses and prefixes to clients.

D. SNTP server address:

True. DHCPv6 can assign the address of an SNTP (Simple Network Time Protocol) server to synchronize time on the client.

Comprehensive and Detailed In-Depth Explanation:

Type 1 LSAs (Router LSAs)are generated byevery OSPF routerto describe itsdirectly connected linksand their states.

TheRouter ID (RID)must beuniquein an OSPF domain; otherwise, OSPF calculations will fail due toambiguous paths.

If two routersin the same areahave thesame Router ID, OSPF will fail to calculateShortest Path First (SPF)correctly, leading to routing inconsistencies.

To prevent this, Huawei routersautomatically detect duplicate Router IDsand prevent OSPF from functioning properly until the issue is resolved.

????Reference:Huawei HCIA-Datacom Study Guide, Chapter on OSPF LSAs and Router ID Uniqueness.

In IS-IS:

Level-1 routerscan only form neighbor relationships with other Level-1 routersin the same area.

Level-2 routerscan form neighbor relationships with other Level-2 routersregardless of area ID.

Level-1-2 routerscan form relationships at both levels depending on the peer's configuration.

So, iftwo Level-1 routershavedifferent area addresses, theycannotestablish a neighbor relationship.

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

“Level-1 routers must have the same area address to establish neighbor relationships. Level-2 routers can peer across different areas.”

(Chapter: IS-IS Protocol Principles – Section: Neighbor Establishment)

Comprehensive and Detailed Step-by-Step Explanation:

BGP Origin Attribute Priority:

The Origin attribute determines the source of the route and affects the selection of the best path.

The priority order is as follows:

IGP (i):Highest priority. Routes injected using the network command.

EGP (e):Lower priority. Routes learned from the EGP protocol.

Incomplete (?):Lowest priority. Routes redistributed into BGP from other protocols.

Correct Option:

A:IGP > EGP > Incompleteis the correct order of priority.

Comprehensive and Detailed Step-by-Step Explanation:

VRRP Virtual MAC Address Format:

The VRRP virtual MAC address is generated using the format:0000-5e00-01XX, whereXXrepresents the VRID in hexadecimal.

Calculation:

VRID = 1 → Hexadecimal =01.

Virtual MAC =0000-5e00-0101.

Correct Option:

C (0000-5e00-0101).

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.