H12-821_V1.0 Huawei HCIP-Datacom-Core Technology V1.0 Free Practice Exam Questions (2025 Updated)

 IGMP:Manages IPv4 multicast group members and runs on the multicast network's last segment (that is, the network segment where a Layer 3 network device is connected to user hosts).

 PIM:Sends multicast data over the network to the multicast device that is connected to group members that have requested the multicast data, implementing multicast data forwarding based on routes.

 IGMP Snooping:Manages and controls the forwarding of multicast data packets to effectively suppress the flooding of multicast data packets on the Layer 2 network.

 IGMP (Internet Group Management Protocol):

IGMP is used by hosts and adjacent multicast routers to establish and maintain multicast group memberships on a local subnet.

It allows a host to inform a multicast router of its desire to receive multicast traffic for a specific group.

It operates at Layer 3 and runs on the last segment of the network.

HCIP-Datacom-Core Technology Training Material (Multicast Fundamentals)​.

 PIM (Protocol Independent Multicast):

PIM is a routing protocol designed for efficient routing of IP multicast traffic. It determines the paths over which multicast packets should be forwarded.

PIM is "protocol-independent" because it uses the underlying unicast routing table for RPF (Reverse Path Forwarding) checks.

It is responsible for distributing multicast data throughout the network.

The mandatory parameters for BGP peer configuration are the peer IP address (peer ip-address) and AS number (as-number). A password is optional for MD5 authentication, and a description is an optional comment for reference. These are not required for establishing the peer relationship ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is NETCONF?

NETCONF (Network Configuration Protocol) is an XML-based protocol used for network device configuration and management.

It enables reading, modifying, deleting, and restoring configurations programmatically.

2. Supported Operations:

Option A: Modifying configurations

Correct.

NETCONF allows you to modify existing configurations on network devices.

Option B: Deleting configurations

Correct.

Configurations can be deleted using NETCONF operations.

Option C: Restoring configurations

Correct.

NETCONF can restore configurations by applying previously saved configuration data.

Option D: Backing up configurations

Correct.

NETCONF can retrieve and save the current configuration as a backup.

3. Summary:

NETCONF supports all listed operations: modifying, deleting, restoring, and backing up configurations.

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

OSPF routers establish neighbor relationships and progress through various states during the adjacency formation process. TheExStart stateis where routers negotiate the master and slaveroles. This negotiation is critical because the master initiates the Data Description (DD) packet exchange process.

Here’s a breakdown of the relevant OSPF states:

ExStart State:

This is the phase where the routers determine which one will act as the master and which will be the slave.

The decision is based on theRouter IDsof the two routers. The router with the higher Router ID becomes the master.

Exchange State:

After the master-slave roles are established, the routers exchange DD packets. These packets contain summaries of the LSAs in their respective LSDBs.

2-way State:

This state indicates that bidirectional communication has been established between the two routers, but it occurs before master-slave negotiation.

Init State:

This is an early state where a router has sent a Hello packet to its neighbor but has not yet received a Hello packet in response.

Key Point:

The negotiation of master and slave roles happens exclusively in theExStart state, makingD. ExStartthe correct answer.

When a stack splits, the MAC addresses of the newly formed stacks do not change immediately. Instead, they retain their original MAC addresses until new ones are reassigned during topology updates. This delayed update prevents immediate conflicts and allows MAD (Multiple Active Detection) to handle any resulting issues ​.

 LSA Lifetime and Deletion

The LS Age field in the LSA header tracks the age of an LSA. When the LS Age reaches its maximum value (3600 seconds), the LSA is marked for deletion. This ensures old or stale LSAs are removed from the network to maintain accurate routing information.

 HCIP-Datacom-Core Reference

Detailed explanation of LS Age behavior and LSA deletion processes can be found in the OSPF LSDB and LSA sections​​.

Theasbr-summarycommand is executed in the global OSPF view to summarize external routes. Theabr-summarycommand is executed in the OSPF area view to summarize routes between areas. By default, theadvertiseparameter is enabled unless explicitly overridden by thenot-advertiseoption ​.

Comprehensive and Detailed Step-by-Step Explanation:

BGP Route Filtering:

BGP provides flexible policies for route filtering to optimize routing table size and reduce network resource usage.

By configuringroute filters, a device can advertise only required routes to peers, thereby improving efficiency.

Purpose of Filtering:

Reduces the routing table size.

Decreases CPU and memory usage on routers.

Limits unnecessary route propagation.

 OSPF Authentication Overview

TheAuth Typefield in the OSPF packet header determines the authentication mode. If theAuth Typeis 1, plaintext authentication is used.

Plaintext authentication involves transmitting the password in an easily readable format, which is less secure compared to MD5.

 HCIP-Datacom-Core Reference

Authentication mechanisms, including plaintext authentication, are detailed in the OSPF security configuration chapter, confirming thatAuth Type = 1corresponds to plaintext​​.

In STP (Spanning Tree Protocol),Bridge Protocol Data Units (BPDUs)contain critical information used in the election and role assignment process, including:

Root Bridge ID– Identifies the current root bridge.

Root Path Cost– Total path cost to reach the root.

Bridge ID– Unique identifier for each switch.These fields are used to determine port roles (root, designated, etc.) and to elect the root bridge.

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

“BPDUs carry the root bridge ID, root path cost, sender’s bridge ID, and port ID. These are used in root bridge election and port role determination.”

(Chapter: Layer 2 Technologies – Section: STP Operation)

IS-IS uses a two-level hierarchy:

Level-1 routersoperate within a single area and cannot exchange routing information with routers in other areas directly.

To reach external areas (the IS-IS backbone or other areas), Level-1 routers rely onLevel-1-2 routers, which perform inter-area route redistribution.

Therefore, a Level-1 routermust use a Level-1-2 routeras a gateway to reach destinations outside its own area.

One multicast MAC address maps to 32 multicast IP addresses due to the limited number of bits used in the mapping process. Specifically, the lower 23 bits of the MAC address map to the lower 23 bits of the multicast IP address, while the high 24 bits of the MAC address are fixed as 0x01005E. Thus, Option B is false ​.

1 – Idle

2 – Connect

3 – OpenSent

4 – OpenConfirm

5 – Established

6 – Active

TheBGP finite state machinedefines how a BGP speaker transitions through various states when establishing and maintaining a BGP session. Below is the role of each state:

Idle (1)– BGP is waiting to start a connection. Initial state of the BGP process.

Connect (2)– BGP initiates a TCP connection to the peer.

OpenSent (3)– TCP connection is established; BGP sends an OPEN message and waits for one from the peer.

OpenConfirm (4)– BGP has received a valid OPEN message and is now expecting a KEEPALIVE.

Established (5)– BGP session is fully established; UPDATE messages can now be exchanged.

Active (6)– If the TCP connection fails in Connect state, BGP transitions to Active and will retry connection.

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

“BGP goes through the following states in order: Idle → Connect → Active → OpenSent → OpenConfirm → Established. The transition depends on the success or failure of TCP connection setup and BGP message exchanges.”

(Chapter: BGP Principles – Section: BGP State Machine)

In a route-policy, attributes such asMED(Multi-Exit Discriminator) andLocal-Preferencecan be used in apply clauses to influence BGP route selection. Attributes likeAS_PathandTagare typically matched or filtered but not directly applied in the apply clause ​.

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

TheNetwork Entity Title (NET)is a unique identifier assigned to an IS-IS router. It is derived from theNetwork Service Access Point (NSAP)address and consists of the following components:

Area Address:

Identifies the area in which the router resides.

Multiple routers in the same IS-IS area must have the same area address.

System ID:

Uniquely identifies the router within the IS-IS area.

The System ID is typically derived from the router's loopback IP address or another unique value.

SEL (Selector Field):

The SEL field is always set to00for IS-IS NETs.

The NET is used by IS-IS for route calculation and to identify the router within the IS-IS domain. Therefore, the statement isTRUE.

Thedefault Hello intervalon an OSPF P2P (Point-to-Point) or Broadcast network is10 seconds, and thedefault Dead intervalis40 seconds.

The Dead interval is the time a router waits without receiving a Hello packet from a neighbor before declaring it down.

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

“For broadcast and P2P network types, the default Hello interval is 10 seconds and the Dead interval is 40 seconds.”

(Chapter: OSPF Interface Types – Section: OSPF Timers)

Comprehensive and Detailed Step-by-Step Explanation:

Distance-Vector Protocols:

Distance-vector protocols determine the best path based on the distance to a destination and periodically share the entire routing table with neighbors.

Example:RIPis a distance-vector protocol.

Link-State Protocols:

Link-state protocols share information about directly connected links, enabling routers to build a complete map of the network.

OSPF(Open Shortest Path First) andIS-IS(Intermediate System to Intermediate System) are link-state protocols that use Dijkstra’s algorithm to calculate the shortest path.

Border Gateway Protocol (BGP):

BGP is neither a distance-vector nor a link-state protocol. Instead, it is classified as apath-vector protocolthat selects the best path based on attributes such as AS-path, next-hop, and local preference.

The IPv6 address 2001:0DBB:B8:0000:C030:0000:0000:09A0:CDEF can be compressed by removing leading zeros in each segment and collapsing consecutive zero groups into ::. The result is 2001:DBB:B8:0:C030::9A0:CDEF ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of BFD Optimization:

BFD (Bidirectional Forwarding Detection) is a protocol that provides rapid detection of link failures.

Optimizing BFD involves adjusting parameters to balance between detection speed and network stability.

2. Analysis of Each Statement:

Option A: After a high priority is configured for BFD packets, BFD packets are preferentially forwarded.

Correct (True Statement).

High priority ensures that BFD packets are not delayed or dropped under congestion, improving detection accuracy.

Option B: To quickly learn about the network status and performance requirements, you can set the interval for sending BFD packets to the minimum value.

Incorrect (False Statement).

Setting the interval to the minimum value can lead to excessive BFD session flapping, which may overload the network or cause instability. The interval should be configured based on network requirements and conditions, rather than set to the minimum.

Option C: On a live network, some devices switch traffic only when a BFD session changes to the Up state... configure a delay to compensate for the time difference.

Correct (True Statement).

This is a valid optimization to avoid issues caused by timing mismatches between BFD and routing protocols.

Option D: If a BFD session flaps, master/backup switchovers are frequently performed... set the WTR time.

Correct (True Statement).

The WTR (Wait to Restore) timer helps stabilize BFD by delaying session recovery after a flap, reducing the risk of frequent switchovers.

3. Summary:

The false statement isB, as setting the BFD packet interval to the minimum can destabilize the network.