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

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of IP Multicast:

IP multicast is a method of delivering data from one source to multiple destinations simultaneously.

Unlike unicast (one-to-one communication) or broadcast (one-to-all communication), multicast isone-to-many, allowing data to be sent only to subscribers (multicast group members).

This significantly conserves bandwidth and reduces the load on the network because the source only sends a single stream of data, which is replicated by multicast routers as needed.

2. Use Cases for IP Multicast:

IP multicast is widely used in network services that involve real-time or large-scale data delivery, such as:

IPTV (Internet Protocol Television):Broadcasting live TV streams.

Real-Time Data Transmission:Delivering stock market data, sensor updates, etc.

Multimedia Conferencing:Supporting group calls, webinars, and online meetings.

3. Why the Statement is TRUE:

IP multicast reduces unnecessary traffic and maximizes efficiency, making it ideal for these types of network services.

For single-hop BFD (Bidirectional Forwarding Detection), the configuration must include the local and remote discriminators to uniquely identify the session endpoints. Additionally, enabling BFD globally is a prerequisite for initiating BFD sessions. Configuring multicast IP addresses isunnecessary for single-hop BFD, as it operates over direct links. Huawei's configuration guidelines specify these requirements to ensure effective deployment and operation of BFD​​.

 Understanding BFD (Bidirectional Forwarding Detection):

BFD is a protocol used to detect link faults quickly between two routers.

Single-hop BFD operates on directly connected links and is commonly used for fast fault detection in routing protocols like OSPF and BGP.

HCIP-Datacom-Core Technology Training Material (BFD Basics and Configuration)​​.

 Mandatory Configurations for Single-Hop BFD:

A. Configure the remote discriminator of a BFD session:The remote discriminator is used to uniquely identify the BFD session at the remote end. This is essential for session establishment.

B. Configure the local discriminator of a BFD session:The local discriminator uniquely identifies the BFD session at the local end. This is required to establish a BFD session.

D. Enable BFD globally:BFD must be enabled globally on the router for the protocol to operate and for session configurations to take effect.

 Optional Configuration:

C. Configure a multicast IP address for BFD:This is not required for single-hop BFD, as it operates over direct links using unicast communication. Multicast is used in other scenarios, like multi-hop BFD.

 Conclusion:The correct configurations for single-hop BFD areA,B, andD.

 BGP Route Flapping and Mitigation

While route flapping is a concern in large-scale networks, BGP employs mechanisms such asRoute Dampeningto 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​​.

Apseudonodein IS-IS is a logical representation of a broadcast network segment (e.g., Ethernet) where theDesignated Intermediate System (DIS)generates an LSP on behalf of the LAN.

Pseudonode LSPs contain:

Interface information(i.e., the interface that connects to the pseudonode)

Neighbor information(adjacencies with other routers on the LAN)

Protocol information(e.g., supported address families)

However,route information is not containedin LSPs generated by pseudonodes because routing information is advertised in theLSPs generated by the routers themselves, not the pseudonode.

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

“Pseudonode LSPs contain information about the broadcast link, including interface and neighbor data. They do not advertise routing entries.”

(Chapter: IS-IS Advanced Features – Section: DIS and Pseudonodes)

Intra-area route calculation in OSPF involves only Router LSAs (Type 1) and Network LSAs (Type 2). Summary LSAs (Type 3) are used for inter-area routes and do not participate in intra-area route calculation. Therefore, the statement is false ​.

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 Step-by-Step Explanation:

OSPF State Machine:

OSPF adjacency progresses through several states:Down > Init > 2-Way > ExStart > Exchange > Loading > Full.

The2-Way stateindicates that routers have exchanged Hello packets but are not forming full adjacencies.

Possible Causes for Staying in the 2-Way State:

Hello Time Values Are Different (A):Mismatched Hello/Dead intervals prevent adjacency establishment.

Area IDs Are Different (B):OSPF routers must belong to the same area to establish adjacency.

Router IDs Conflict (C):While Router ID conflicts cause other issues, they do not result in the 2-Way state.

N-bit and E-bit Are the Same (D):Matching N-bit/E-bit values are normal and do not cause problems.

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

To establish an OSPF neighbor relationship, the following conditions must be met:

The routers must share a common network segment.

Their Hello and Dead intervals must match.

Their OSPF network types must be compatible.

The IP subnet masks must match.

If two OSPF routers are ondifferent network segmentsand havedifferent subnet masks, one solution is to change the OSPFnetwork typetoPoint-to-Point (P2P)on both interfaces.

Point-to-Point (P2P):

In a P2P network type, OSPF ignores the subnet mask mismatch and establishes the neighbor relationship regardless of the network mask.

This is ideal for directly connected links between two routers.

NBMA (Non-Broadcast Multi-Access):

This network type is used for networks like Frame Relay or ATM, where a single physical interface connects to multiple neighbors.

It is not applicable to solving subnet mask mismatches for a single link.

P2MP (Point-to-Multipoint):

This type treats the link as multiple P2P links. It is mainly used in hub-and-spoke topologies.

While it can be configured to solve subnet mask mismatches, it is more complex and less commonly used compared to the P2P type.

Broadcast:

This type requires all routers on the same segment to agree on subnet masks, so it cannot resolve the subnet mask mismatch issue.

Therefore, the correct answer isA. Point-to-point.

Comprehensive and Detailed Step-by-Step Explanation:

Analysis of VRRP Configuration:

Option A (Preemption):Correct. The output explicitly states that preemption is enabled.

Option C (Authentication):Correct. Authentication is enabled using MD5.

Option D (Group ID):Correct. The VRRP group ID is explicitly stated as 1.

False Statement:

Option B (mVRRP Group):The output does not indicate this is anmVRRP (Multicast VRRP)group. This feature must be explicitly configured and is not enabled by default.

 R1 is a Level-1 router in Area 49.0001, while R4 is in Area 49.0004. Level-1 routers only maintain LSDBs for their own area and do not contain LSPs from other areas, such as R4’s LSP.

 R2 is a Level-1-2 router, so it maintains LSDBs for both Area 49.0001 (Level-1) and Level-2 domains, which include LSPs from R4.

 R3 and R4, as Level-2 routers, exchange LSPs with each other within the Level-2 domain.

 Thus, the LSDB of R1 does not include R4’s LSP ​.

On Huawei devices, multiple BGP processes can be configured on the same router, but they are typically used for specific use cases such as multi-instance deployments or virtual routers. This flexibility is supported by Huawei's routing protocols ​.

OSPF process IDs are locally significant and do not need to match between routers to form neighbor relationships. The other statements correctly describe the behavior of OSPF multi-instances, making Option C false ​.

 DIS and DR Election

The IS-IS Designated Intermediate System (DIS) is responsible for generating and updating pseudonode LSPs on a broadcast network.

Unlike OSPF DR, the IS-IS DIS does not preempt by default. This behavior avoids unnecessary flapping in the network due to frequent DIS re-elections.

 HCIP-Datacom-Core Reference

The characteristics of DIS and DR behavior are explained in IS-IS network operation chapters​​.

Comprehensive and Detailed Step-by-Step Explanation:

Overview of IGMP Versions:

IGMPv1:The simplest version, supports basic group membership management using Report messages but lacks Leave messages.

IGMPv2:Adds features like Leave messages and Group-Specific Queries.

IGMPv3:Supports specifying multicast sources for Source-Specific Multicast (SSM).

Feature Supported by All Versions:

Report messagesare fundamental to IGMP functionality and are supported in all three versions.

Features Not Supported by All Versions:

Group-Specific Queries (A):Supported in IGMPv2 and IGMPv3.

Leave Messages (B):Introduced in IGMPv2.

Specifying Multicast Sources (D):Introduced in IGMPv3.

Comprehensive and Detailed Step-by-Step Explanation:

Analysis of BGP Attributes:

Original Next Hop:The output shows that the original next hop of the route is 172.16.1.2. (A is correct).

Local Router ID:The local BGP router ID is 10.1.1.1, as displayed. (B is correct).

Local AS Number:The local AS number is 100, as displayed. (C is correct).

Incorrect Option:

Local_Pref:Although Local_Pref is an important attribute, this route is marked as invalid due to "IP unreachable" and thus cannot be preferentially selected.

If VRRP is not configured to track uplink interfaces, a failure in the master device's uplink or link will not trigger a switchover, resulting in a traffic blackhole. The VRRP mechanism relies on interface tracking to monitor connectivity and ensure role transitions upon faults. Without this configuration, no failover occurs, and traffic directed toward the master device is lost ​.

Inter-area route calculation in OSPF involves Summary LSAs (Type 3) for summarizing routes across areas and ASBR Summary LSAs (Type 4) for locating ASBRs. While Router LSAs and Network LSAs describe the internal structure of an area, they do not directly participate in inter-area route calculation. Thus, the statement that only Router, Network, and Summary LSAs are involved is false ​.

 Silent Interface Explanation

Thesilent-interfacecommand is used to prevent OSPF from sending or receiving OSPF packets on the specified interface (GE 0/0/1). This disables OSPF adjacency establishment and stops route advertisement for that interface.

 Network Observations

Statement A: R2 can access the server.This is correct, as the silent interface does not impact data traffic, only OSPF-related communication.

Statement B: GE 0/0/1 of R1 cannot send OSPF packets.Correct due to thesilent-interfaceconfiguration.

Statement C: The network segment to which GE 0/0/1 of R1 belongs cannot be advertised.This is correct, as the silent interface prevents route advertisement.

Statement D: GE 0/0/1 of R1 cannot accept OSPF packets.Correct, as the silent interface configuration blocks packet reception.

 HCIP-Datacom-Core Reference

OSPF interface command behavior is outlined in the configuration and lab examples sections​​.

Explanation of IS-IS Packet Types and Synchronization Process:

In the given scenario, R2 requests LSPs from R1 to synchronize its Link State Database (LSDB). The following IS-IS packet types are involved in this synchronization process:

1. P2P IIH (Point-to-Point IS-IS Hello):

Purpose:Establishes and maintains IS-IS neighbor relationships.

Step:This packet is exchanged initially to detect and maintain the adjacency between R1 and R2.

2. PSNP (Partial Sequence Number PDU):

Purpose:Requests missing or outdated LSPs (Link State PDUs) from a neighbor to synchronize the LSDB.

Step:In this case, R2 sends a PSNP to R1 to request the missing or outdated LSP.

3. LSP (Link State PDU):

Purpose:Contains routing information and is used to update the LSDB.

Step:R1 sends the requested LSPs to R2 for synchronization.

4. CSNP (Complete Sequence Number PDU):

Purpose:Lists all LSPs in the sender's LSDB to help neighbors verify and request missing LSPs.

Step:R1 sends a CSNP during retransmission timeout to notify R2 of its LSPs.

The forwarding plane of a switch consists of data forwarding hardware, such as line cards or forwarding engines, and is responsible for tasks like encapsulating/decapsulating packets, providing high-speed data channels, and collecting packet statistics. However, main control boards are part of the control plane, not the forwarding plane. This distinction ensures a separation of data forwarding and control functionalities ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. How Firewalls Match Security Policies:

Firewalls usesecurity policiesto define rules for filtering traffic.

Each policy containsmatching conditions(e.g., source IP, destination IP, protocol, etc.) and anaction(e.g., permit or deny).

Traffic is evaluated against these policies in sequential order, and the first matching policy is applied.

2. Analysis of Each Statement:

Option A: Multiple values can be configured for a single matching condition, and the values are logically ANDed.

Incorrect.

Multiple values for a single matching condition (e.g., multiple source IPs) are logicallyORed, not ANDed. For example, traffic from any of the specified source IPs matches the policy.

Option B: If a security policy contains multiple matching conditions, the relationship between them is AND.

Correct.

When a policy has multiple matching conditions (e.g., source IP AND destination IP AND protocol), all conditions must be met for the policy to match.

Option C: The system has a default security policy named default, where all matching conditions are any and the default action is permit.

Incorrect.

The default security policy typically denies all traffic unless explicitly permitted by user-defined policies.

Option D: When multiple security policy rules are configured, they are sorted in a list by configuration sequence by default. A security policy rule configured earlier is placed higher in the list and has a higher priority.

Correct.

Security policies are processed in sequential order based on their configuration sequence. Policies configured earlier have higher priority and are evaluated first.

3. Summary:

The correct statements areBandD.

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 Step-by-Step Explanation:

Understanding the ACL Configuration:

ACL Number:3001 is an advanced ACL.

Rule Description:The rule permits ICMP packets with the following criteria:

Source IP:192.168.1.3(host-specific).

Destination IP:192.168.2.0/24(entire subnet).

Analysis of Each Option:

Option A:True. ICMP packets from 192.168.1.3 to 192.168.2.200 (within the subnet) are permitted.

Option B:True. Packets from 192.168.1.2 (not matching the source) are denied by default.

Option C:False. The ACL only permits ICMP packets, not general IP packets.

Option D:True. The ACL is identified by the number 3001.

Thesilent-interfacecommand disables the sending of OSPF packets, including Hello packets, on the specified interface, which prevents the establishment of OSPF neighbor relationships. However, the interface can still advertise directly connected routes through other interfaces, making Option C incorrect ​.

 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.

Let's break it down step by step based on Huawei's routing protocol behavior:

R1imports thedirect route 10.1.1.0/24intoOSPF.

This route is advertised byR1 to R2 and R3viaOSPF.

BothR2 and R3are runningIS-IS, andbidirectional route redistributionis configured between OSPF and IS-IS.

R2 and R3 bothre-advertisethe OSPF-learned route into IS-IS and then potentiallyre-learnit back from the IS-IS domain, causingredistribution loopsunless properly controlled.

Now, the question focuses onR3’s routing table:

R3 already learns the routedirectly via OSPFfrom R1.

It also learns the same route again viaIS-ISfrom R2 (looped back due to bidirectional redistribution).

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

“OSPF ASE routes are assigned a default preference of 150. If a route is redistributed from another protocol (like IS-IS) into OSPF, and then re-learned, it is considered an ASE route.”(Chapter: OSPF Advanced Features – Section: Route Redistribution Behavior)

Comprehensive and Detailed Step-by-Step Explanation:

Portal Authentication:

Portal authentication uses a web-based mechanism where clients are redirected to a login page.

Communication between the access device and Portal server uses HTTP or HTTPS protocols.

Correct Statements:

Option A:HTTP or HTTPS is used for Portal authentication.

Option D:Portal protocol packets are transmitted overTCPfor reliable communication.

Incorrect Statements:

Option B:Port 2000 is not the default for processing Portal packets.

Option C:The default destination port for communication with the Portal server is not 50100.

Application Specific Packet Filtering (ASPF) is a feature that allows the firewall to understand and handle multi-channel protocols such as FTP, H.323, and SIP. ASPF inspects the controlchannel to dynamically create temporary rules for the data channels, enabling the firewall to secure and manage complex application protocols. This feature ensures that appropriate security policies are applied to these multi-channel applications ​.

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

In OSPF,Link State Advertisements (LSAs)are used to exchange routing and topology information. Each LSA in the OSPF network is uniquely identified using a3-tuple identifier, which consists of:

Link State ID:

The Link State ID uniquely identifies the LSA within the OSPF area. Its value depends on the LSA type. For example, for a Router LSA, the Link State ID is the originating router’s Router ID.

Advertising Router:

This is the Router ID of the router that generated the LSA. It identifies which router is responsible for creating and advertising this LSA.

LSType:

This field identifies the type of LSA (e.g., Router LSA, Network LSA, Summary LSA, AS-External LSA, etc.). It is crucial for interpreting the purpose and content of the LSA.

TheLS Sequence Numberis not part of the 3-tuple that uniquely identifies the LSA. Instead, it is used to determine the most recent version of the LSA in case there are multiple instances of the same LSA.

BFD control packets are encapsulated in UDP packets, and the destination port number for multi-hop BFD control packets is 4784. This is a standardized port for multi-hop BFD operation ​.

Comprehensive and Detailed Step-by-Step Explanation:

Bidirectional Forwarding Detection (BFD):

BFD is a lightweight protocol that provides rapid fault detection on links independent of the underlying routing protocol or media.

Requirements for BFD:

Both devices at the endpoints of the link must support and configure BFD for it to operate.

If one device does not support BFD, the feature cannot be used for link detection.

The native AC (Access Controller) function in Huawei's agile switches enables wired and wireless convergence. This integration allows the agile switch to act as both a wired network switch and a wireless controller, managing all traffic centrally. This architecture simplifies network management and improves efficiency, making the statement true ​.

 Transitive vs. Non-Transitive Attributes

The Community attribute is atransitive optional attribute, meaning that if a router receives a route with this attribute and does not understand its purpose, the router retains and propagates it to other peers.

Other options, such as AS_Path and MED, are well-defined mandatory or optional attributes with specific purposes.

 HCIP-Datacom-Core Reference

The behavior of optional transitive attributes is detailed in the BGP protocol and attribute chapters​​.

The Designated Intermediate System (DIS) in an IS-IS broadcast network sends Complete Sequence Number PDUs (CSNPs) at a default interval of 30 seconds. This interval ensures periodic synchronization of the Link State Database (LSDB) among IS-IS neighbors ​.

In Huawei firewalls, the security level of a zone can be reconfigured by an administrator, making the statement that it cannot be changed false. Other statements accurately describe security level restrictions or defaults ​.

The monitoring plane's primary role is environmental monitoring, ensuring the stability of the system. Functions like voltage monitoring, temperature tracking, fan speed control, and power management are standard. These are independent of the forwarding or control planes and critical for maintaining device health in network operations ​.

 MQC and PBR

MQC (Modular QoS Command-Line Interface): Applied to interfaces for classifying and controlling traffic.

PBR (Policy-Based Routing): Used to influence packet forwarding based on policies rather than traditional routing tables.

Both MQC and PBR can be configured on device interfaces to filter incoming/outgoing packets or control their forwarding paths.

 HCIP-Datacom-Core Reference

The use of MQC and PBR on device interfaces is elaborated in the QoS and routing control chapters​​.

Comprehensive and Detailed Step-by-Step Explanation:

OSPF Route Summarization:

Route summarization combines multiple specific routes into a single summary route. This reduces the number of LSAs advertised between OSPF areas, especially Type 3 LSAs.

Benefits of Route Summarization:

Reduces the size of the OSPF database and routing table.

Minimizes the processing overhead on routers by decreasing the number of routing entries.

Improves the scalability of the OSPF network.

ASBR Function:

The ASBR advertises external routes into OSPF and can summarize routes at area boundaries or during redistribution.

The output shows that the router with the IP10.0.12.2is the Backup Designated Router (BDR), as indicated in theState: BDRfield. The router ID is10.0.2.2, the interface cost is 1, and the IP address of the interface is10.0.12.2. Hence, C is the correct answer ​.

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.

InIPv6, fragmentation is handledonly at the source node. Intermediate routersdo not fragment packets. Instead, if a packet is too large for the next link, the router sends back anICMPv6 Packet Too Bigmessage to the source, which then adjusts its packet size.

This design:

Reduces processing load on intermediate devices.

Supports Path MTU Discovery (PMTUD).

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

“In IPv6, routers do not perform fragmentation. Only the source device fragments packets if needed, based on ICMPv6 feedback.”

(Chapter: IPv6 Fundamentals – Section: Fragmentation and PMTUD)

Thefilter-policycommand 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 ​.

 Neighbor Discovery Protocol (NDP):

NDP is a key protocol in the IPv6 protocol suite, replacing ARP (Address Resolution Protocol) in IPv4.

It operates using ICMPv6 (Internet Control Message Protocol for IPv6) and is critical for managing interactions between IPv6 nodes on the same link.

HCIP-Datacom-Core Technology Training Material (NDP Functions and Features)​​.

 NDP Features and Functions:

A. Address resolution:NDP resolves IPv6 addresses into MAC addresses, similar to ARP in IPv4. It uses Neighbor Solicitation (NS) and Neighbor Advertisement (NA) messages for this purpose.Reference:HCIP-Datacom-Core Technology Training Material (Address Resolution in IPv6)​.

B. Neighbor state tracing:NDP tracks the state of neighbors to determine their reachability. It maintains a neighbor cache and uses NS/NA messages to verify whether neighbors are reachable.Reference:HCIP-Datacom-Core Technology Training Material (Neighbor Reachability in IPv6)​.

C. Duplicate address detection (DAD):NDP ensures that IPv6 addresses are unique within a network. Before assigning an address to an interface, DAD is used to verify that no other node is using the same address. This is done via NS messages.Reference:HCIP-Datacom-Core Technology Training Material (IPv6 Address Assignment and DAD)​.

D. Redirection:NDP provides redirection functionality to inform hosts of a better first-hop router for reaching a particular destination. It uses ICMPv6 Redirect messages for this purpose.Reference:HCIP-Datacom-Core Technology Training Material (NDP Redirect Functionality)​.

 Conclusion:NDP supports all the mentioned functions and features:Address resolution,Neighbor state tracing,Duplicate address detection, andRedirection, making it indispensable for IPv6 networks.

BGP, IS-IS, and OSPF support the configuration of default routes through specific command configurations. For example, BGP uses thedefault-originatecommand, IS-IS uses adefault-route-advertisemethod, and OSPF can advertise default routes usingdefault-information originate. ICMP, however, is not a routing protocol and does not support this functionality ​.

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 ​.

The scenario describes a mismatch in OSPF network types between two connected routers: one set to Point-to-Point (P2P) and the other set to Point-to-Multipoint (P2MP). While aligning Hello intervals may seem sufficient for establishing an OSPF neighbor relationship, the fundamental mismatch in network types introduces issues.

OSPF Network Types

P2P: Assumes a direct connection with a single neighbor, uses faster convergence and simpler LSDB synchronization.

P2MP: Supports multiple neighbors on a single interface, requiring different handling for DR/BDR roles and LSDB updates.

Impact of Network Type Mismatch

If Hello intervals are aligned, adjacency establishment might occur. However, mismatched network types affect neighbor role assignment and LSDB synchronization.

P2P expects a direct link and would handle updates differently than P2MP, which assumes multiple neighbors. This leads to inconsistencies in route calculation and forwarding.

HCIP-Datacom-Core Reference

OSPF Basics and Configuration​clearly outlines the criticality of consistent network type configuration for stable OSPF operation.

Lab examples in the HCIP Datacom Lab Guide​further demonstrate the consequences of such mismatches, including unstable neighbor states and incomplete LSDB synchronization.

Hence, the statement that neighbor relationships and LSDB synchronization remain unaffected is incorrect. Proper OSPF operation requires matching network types in addition to aligned Hello intervals.

In Layer 3 roaming scenarios, STAs (stations) remain on different subnets before and after roaming. To ensure that user traffic reaches the original subnet, it must be tunneled back over a CAPWAP tunnel. This technique prevents disruptions in communication and enables seamless roaming. Huawei’s Layer 3 roaming design guidelines emphasize the use of CAPWAP tunnels for user traffic forwarding ​.

In OSPF (Open Shortest Path First), each router maintains aLink-State Database (LSDB), which must be synchronized with other routers in the same area. When an OSPF router receives anLSA (Link-State Advertisement)that it doesnot already have in its LSDB, it takes the following steps:

It updates its LSDB with the new LSA.

It floods the LSA to all its other OSPF neighbors (except the one from which it received the LSA).

This ensures that all routers in the OSPF area eventually converge to the same network topology.

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

“When an LSA is received and it is newer or not present in the LSDB, the router updates the LSDB and floods the LSA to other neighbors to ensure database synchronization.”

(Chapter: OSPF Fundamentals – Section: LSDB Synchronization)

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 ​.

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.

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

To answer this question, we need to understand the roles of OSPF routers:

Area Border Router (ABR):

An ABR is a router that connects multiple OSPF areas. It has at least one interface in the backbone area (Area 0) and one or more interfaces in other OSPF areas.

The ABR performs summarization between areas and propagates routing information between them.

Backup Router (BR):

The term "BR" does not exist in OSPF terminology. Instead, OSPF uses the term "Backup Designated Router (BDR)." The BDR is a backup to the Designated Router (DR) in a specific OSPF broadcast or NBMA (Non-Broadcast Multi-Access) network. The BDR takes over the DR's responsibilities if the DR fails.

Key Clarification:

An ABR is related to the hierarchical structure of OSPF areas and is not tied to the DR/BDR election process.

A router can function as an ABR without ever being a DR or BDR, as these are separate roles.

Therefore, the statement that an ABR must also be a BR isFALSE.

 IPv6 Address Behavior

Manually configured link-local addressesdo not have a higher prioritythan automatically generated ones; they coexist and are equally preferred for local communication.

The other statements are true:

A.Link-local addresses can use the EUI-64 method for quick generation.

B.Anycast addresses are only used as destination addresses.

C.An interface can have multiple global unicast addresses with different prefixes.

 HCIP-Datacom-Core Reference

IPv6 address types and priority behaviors are detailed in the IPv6 addressing sections​​.

A is correct– Removing unused accounts helpsminimize the risk surface.

B is false– Email isnot a secure methodfor transferring sensitive information like passwords, even if encrypted.

C is correct–Unique administrator accountshelp with accountability and tracking.

D is false–Long-term password validityreduces security. Passwords should be rotated regularly.

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

“To secure admin access, avoid account sharing, delete inactive users, and periodically update credentials through secure channels.”

(Chapter: Device Security – Section: Account Management)

By default, BGP does not automatically summarize imported routes. Route summarization must be explicitly configured using thesummaryor similar commands ​.

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.

A screenshot of a computer Description automatically generated

Explanation of VRRP Roles and Their Functions:

InVRRP (Virtual Router Redundancy Protocol), devices are assigned roles as eitherMasterorBackupafter an election process. Each role has specific responsibilities to ensure the availability of the virtual IP address.

Matching Roles and Mechanisms:

Master:

Periodically send VRRP Advertisement packets.

The Master device sends advertisement packets to inform Backup devices that it is active.

Respond to an ARP request destined for a virtual IP address with an ARP reply carrying the virtual MAC address.

The Master device is responsible for responding to ARP requests for the virtual IP and forwarding traffic for it.

Backup:

Transition from Master to Backup immediately if a VRRP Advertisement packet with a higher priority is received.

A Backup device becomes Master only if the current Master stops sending advertisement packets or has a lower priority.

Discard IP packets destined for the virtual IP address.

Backup devices do not process traffic for the virtual IP address unless they become the Master.

When the router ID is configured in both the system view and the BGP view, the router ID in the BGP view takes precedence because BGP-specific configurations override global settings. This ensures that BGP operates with the most relevant configurations ​.

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.

The preference of routing protocols determines the selection order of routes when a router receives multiple routes to the same destination from different routing protocols. For instance, OSPF has a higher preference over RIP, so OSPF routes will be selected first. Huawei routing preferences confirm this behavior ​.

Thesummary automaticcommand in BGP is used to enable automatic summarization of routes, particularly for classful networks. However, manual summarization takes precedence over automatic summarization when both are configured. This makes the statement claiming automatic summarization takes precedence false ​.

The question indicates that a router performs a lookup in its FIB table for a packet and determines that the tunnel ID in the matching entry is 0, suggesting that the packet needs to be forwarded through a tunnel such as an MPLS tunnel. However, this is a misunderstanding of the FIB functionality.

FIB Table OverviewThe Forwarding Information Base (FIB) is used to make packet-forwarding decisions. Entries in the FIB include next-hop information, which can be directly linked to an interface or a tunnel.

If theTunnel IDis0, it indicates that the packet is forwarded via a normal routing path and not through a tunnel.

For MPLS or other tunnels, the Tunnel ID would have a non-zero value pointing to the associated tunnel.

MPLS Tunnel OperationWhen a router forwards packets through an MPLS tunnel, a label-switched path (LSP) is set up. The FIB would reflect specific tunnel identifiers for packets that need such encapsulation.

HCIP-Datacom-Core Reference

Routing Principles and MPLS​explain the forwarding mechanisms clearly, stating that if a packet is routed normally, the tunnel ID remains0.

The section on MPLS​clarifies the encapsulation process and the role of tunnel identifiers.

Hence, the claim in the question is incorrect. A Tunnel ID of0implies no tunneling is required, and normal IP forwarding occurs

 pat

 trust

 12.1.1.0

 inner

Router LSAs (Type 1) and Network LSAs (Type 2) are advertised only within a single OSPF area, as they describe the topology within the area. In contrast, Summary LSAs (Type 3) and AS External LSAs (Type 5) are used for inter-area and external routing, respectively ​.

In the IS-IS protocol, TLV 129 (IPv4 interface address) is used to describe the IP address of an interface. Each TLV type carries specific information, and TLV 129 specifically relates to interface IP addresses ​.

Comprehensive and Detailed Step-by-Step Explanation:

BGP ConnectRetry Timer:

The ConnectRetry timer is used when establishing a TCP connection between BGP peers.

If the connection is successful, the timer is disabled.

If the connection fails, the timer restarts, and the router attempts to reconnect after the timer expires.

Behavior:

This timer prevents excessive connection attempts and ensures efficient resource utilization.

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 ​.

In the provided configuration, IS-IS is enabled onLoopback0but not onLoopback3of R2. As a result, R2 will advertise the route10.0.2.2/32(fromLoopback0) to R1 through IS-IS. However, the route10.0.2.3/32will not be advertised because IS-IS is not enabled on that loopback interface. Theimport-route directcommand does not override this behavior ​.

 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​​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is L2TP (Layer 2 Tunneling Protocol)?

L2TP is a tunneling protocol used to transport Layer 2 frames over IP networks.

It is commonly used to establish VPNs but does not provide built-in encryption or security for the transmitted data.

2. Why L2TP Requires Additional Security Measures:

Since L2TP does not encrypt traffic, it is vulnerable to eavesdropping and tampering.

To secure L2TP tunnels, it is often paired with IPsec, which provides strong encryption and authentication. The combination of L2TP and IPsec is known asL2TP/IPsec.

3. Why the Statement is TRUE:

The statement accurately describes the limitation of L2TP (lack of encryption) and the need for additional security measures like IPsec.

The correct command for configuring the VRRP (Virtual Router Redundancy Protocol) preemption delay isvrrp vrid 1 preempt-delay 20. This command sets the delay before a higher-priority VRRP router preempts the master role, ensuring stable operation during network transitions ​.

Comprehensive and Detailed Step-by-Step Explanation:

IS-IS Three-Way Handshake:

IS-IS uses athree-way handshaketo establish neighbor relationships.

This process is applied on bothpoint-to-point (P2P)andbroadcastnetwork types to confirm bidirectional communication.

P2P Networks:

Routers directly exchange IS-IS Hello (IIH) packets to establish adjacency.

Broadcast Networks:

IS-IS also uses the three-way handshake on broadcast networks to ensure that the Designated Intermediate System (DIS) election and adjacency formation are correct.

Multi-channel protocols such as H.323 and FTP use separate control and data channels. H.323 uses different channels for call signaling and media streaming, while FTP uses a control channel for commands and a data channel for file transfers. Telnet and SMTP are single-channel protocols ​.

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 ​.

IGP routes can be injected into BGP using multiple methods, not just thenetworkcommand. Theimport-routecommand can also be used to redistribute IGP routes into BGP. Thenetworkcommand requires the route to exist in the routing table, whileimport-routeallows direct redistribution ​.

ICMPv6 messages are classified into two types: error messages (e.g., Destination Unreachable, Time Exceeded) and informational messages (e.g., Echo Request, Echo Reply). This classification is fundamental to ICMPv6's operation ​.

Comprehensive and Detailed Step-by-Step Explanation:

Session Creation in Firewalls:

Firewalls create session entries for packets requiring stateful inspection (e.g., TCP, UDP, ICMP, and GRE).

Subsequent fragmentsof large packets do not require new sessions. Instead, they are processed based on the session created for the first fragment.

Correct Option:

C (Subsequent Fragment):Does not trigger a new session entry as it belongs to an existing session.

Comprehensive and Detailed Step-by-Step Explanation:

Firewall Session Table:

A session table is used to track active sessions. If a session remains idle for longer than the configured aging time, it is removed to free resources and enhance security.

TCP Session Timeout:

If the interval between two packets exceeds the session timeout, the firewall deletes the session information, requiring the session to be re-established.

SSL VPN and Its Functionality:

SSL VPN (Secure Sockets Layer Virtual Private Network) provides secure remote access to a network using SSL/TLS protocols.

SSL VPN operates at theApplication Layerof the OSI model. It enables secure communication for applications like web browsers, email clients, and file sharing.

Unlike IPsec VPN, which operates at the Network Layer, SSL VPN focuses on application-specific encryption and authentication.

HCIP-Security Training Material (VPN Basics and SSL VPN Configuration)​​.

BFD control packets are encapsulated in UDP packets, and the destination port number for multi-hop BFD control packets is 4784. This is a standardized port for multi-hop BFD operation ​.

To compress the IPv6 address 2001:0DB8:0000:C030:0000:0000:09A0, the following rules are applied:

Remove leading zeros in each hextet (e.g., 0DB8 becomes DB8).

Replace contiguous blocks of zeros with :: (only once in the address).Thus, the compressed form is 2001:DB8:0:C030::9A0 ​.

GRE (Generic Routing Encapsulation) is not a Layer 2 VPN technology. Instead, it is a Layer 3 tunneling protocol used to encapsulate a wide variety of network layer protocols inside point-to-point connections. GRE is commonly used for creating VPN tunnels across IP networks,allowing for the transport of various types of payloads. This misunderstanding about GRE being a Layer 2 technology contradicts its definition and typical application ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding IGMP Version Compatibility:

IGMP (Internet Group Management Protocol) supports multiple versions, such as IGMPv1, IGMPv2, and IGMPv3.

A device running alater versionof IGMP is backward-compatible and can identify Report messages from earlier versions.

However, a device running anearlier versionof IGMP cannot recognize the newer features or formats of later IGMP versions.

2. Best Practice:

To avoid compatibility issues, the IGMP version configured on the switch should be thesame as or later thanthe version used by the member hosts in the network.

3. Why the Statement is TRUE:

The statement is correct because it describes the compatibility behavior of IGMP versions and advises setting the switch IGMP version appropriately.

 Understanding BGP Route Summarization:

In Border Gateway Protocol (BGP),route summarizationis a technique used to aggregate multiple specific prefixes into a broader summary prefix. This reduces the size of routing tables and improves routing efficiency.

Summarization helps to hide unnecessary details from other parts of the network while still maintaining connectivity.

HCIP-Datacom-Core Technology Training Material (BGP Route Summarization)​​.

 Suppressing Specific Routes:

When summarizing routes, thesuppress-spec-map keywordis used to suppress specific prefixes so that only the summarized route is advertised.

The suppressed routes are not advertised to BGP peers; instead, only the summary route is propagated.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is the BFD Echo Function?

BFD (Bidirectional Forwarding Detection) is used to detect link failures.

TheEcho functionis an optional feature that tests link connectivity by looping back packets sent from the local device through the forwarding path.

2. Analysis of Each Statement:

Option A: If URPF is enabled on the peer end, BFD packets may be incorrectly discarded on the peer end.

Correct.

URPF (Unicast Reverse Path Forwarding) checks whether the source IP address of an incoming packet is reachable via the interface it was received on. Since the Echo function uses loopback packets, this can conflict with URPF, causing the packets to be dropped.

Option B: In the BFD Echo function, the device uses the IP address of the outbound interface as the source IP address by default.

Correct.

By default, the outbound interface's IP address is used as the source address for BFD Echo packets.

Option C: The BFD Echo function applies only to single-hop BFD sessions.

Incorrect.

The BFD Echo function can be used for both single-hop and multi-hop BFD sessions.

Option D: When configuring a BFD session supporting the BFD Echo function, you need to configure both the local and remote discriminators.

Incorrect.

The BFD Echo function is locally configured and does not require setting remote discriminators. The function operates independently of the remote device's configuration.

3. Summary:

The correct statements areAandB.

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.

Option A correctly configures the DHCP relay agent (AC) to forward requests to the DHCP server using VLAN 10.

Option B correctly configures the DHCP server (AR) with the correct IP pool (10.1.1.0/24), gateway, and excluded IP addresses. The static route to10.1.1.0through172.21.1.1ensures proper routing ​.

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