H12-821_V1.0 Sample Questions Answers

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding the AS-Path Filter:

The as-path-filter command is used in BGP to filter routes based on the AS_PATH attribute.

In this configuration:

The filter si is defined with the regular expression _65500$.

The _65500$ expression specifies that the AS_PATH must end with 65500, meaning that the route's last hop must have passed through AS 65500.

2. Option Analysis:

Option A: It accepts only the routes whose AS_Path contains AS 65500.

Incorrect.

The _65500$ filter specifically matches routes where AS 65500 is the last AS in the AS_PATH. A route may contain AS 65500 somewhere in the middle of the AS_PATH but will not match this filter unless it is the last AS.

Option B: It accepts only the routes originated from AS 65500.

Incorrect.

Routes that originate from AS 65500 have an AS_PATH that starts with 65500. However, the filter _65500$ only matches routes where AS 65500 is the last AS, not the first AS.

Option C: It accepts only the routes that last pass through AS 65500.

Correct.

The _65500$ filter ensures that the AS_PATH ends with 65500. This means that the route must have last passed through AS 65500 before being received by the local BGP router.

Option D: It accepts only the routes forwarded by AS 65500.

Incorrect.

While AS 65500 may forward the route, this is not what the filter _65500$ specifically checks for. It only ensures that AS 65500 is the last AS in the AS_PATH.

3. Summary:

The as-path-filter with _65500$ accepts only the routes where AS 65500 is the last AS in the AS_PATH.

Huawei HCIA-Datacom Study Guide, Chapter "BGP Filtering Mechanisms"

RFC 4271: Border Gateway Protocol 4 (BGP-4)

Comprehensive and Detailed Step-by-Step Explanation:

OSPF Route Preference Hierarchy:

OSPF uses the following preference order for route types when the prefix is the same:

Intra-area routes (D): Routes within the same OSPF area have the highest priority.

Inter-area routes (B): Routes between different OSPF areas are preferred after intra-area routes.

Type 1 external routes (A): External routes redistributed into OSPF, considering the internal OSPF cost to the ASBR.

Type 2 external routes (C): External routes redistributed into OSPF, ignoring the internal OSPF cost to the ASBR.

Lowest Priority:

Type 2 external routes (C) are given the lowest priority because they represent external information that does not consider internal OSPF costs.

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.

Comprehensive and Detailed In-Depth Explanation:

SNMP (Simple Network Management Protocol) v3is a moresecureversion of SNMP, supportingauthentication and encryption.

If theNMS is not receiving SNMPv3 traps, possible causes include:

A. FALSE→ TheSNMP version mismatch does not affect traps; devices can send SNMPv2 traps even when using SNMPv3.

B. TRUE→ If theSNMPv3 password is incorrect, authentication will fail, and traps will not be processed by the NMS.

C. FALSE→ The size of packets sent by theNMSdoes not affectincoming SNMP trapsfrom the router.

D. TRUE→ Thecommunity namemust match on both theNMS and the router, or traps will be ignored.

????Reference:Huawei HCIA-Datacom Study Guide, SNMPv3 Configuration and Authentication.

By default, Huawei firewalls create security zones such as Trust, Untrust, and Local. The DMZ (Demilitarized Zone) is a security zone explicitly created by users. A DMZ is used to isolateaninternal network from the external one, providing an additional layer of security by placing public-facing services (e.g., web servers) in this intermediary zone. This setup ensures that if a public-facing service is compromised, the internal network remains secure. Huawei Firewall configuration steps confirm this zoning principle, making DMZ creation an explicit user-driven action ​.

Hello packets are the most basic and essential type of OSPF packets used for the following purposes:

Neighbor discovery– Routers use Hello packets to discover other OSPF routers on the same link.

Neighbor relationship establishment– When two routers exchange matching Hello packets, they move from the "Init" state to "2-Way" and further into adjacency states.

Neighbor relationship maintenance– Hello packets are sent periodically to ensure that neighbors are still reachable. If Hello packets are missed within the dead interval, the neighbor is considered down.

Neighbor deletionis not a direct function of Hello packets. Neighbor deletion results indirectly from missed Hello packets.

According to BGP route selection rules, a higherLocal_Prefvalue indicates a more preferred route. This rule is used to influence traffic flow within an autonomous system (AS), giving preference to routes with a higherLocal_Preffor outgoing traffic ​.

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.

Inasynchronousmode, the local device sends BFD control packets at predefined intervals, and the remote device monitors the receipt of these packets to detect connectivity issues. This is one of the two operating modes in BFD, the other beingdemandmode ​.

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

In IS-IS, theinterface costis a metric used to determine the best path to a destination. Lower-cost paths are preferred over higher-cost paths. By default, IS-IS interface costs can range from1 to 63.

Default Cost Range:

IS-IS allows the configuration of interface costs within the range of1–63by default. This range is sufficient for most networks.

Maximum Configurable Cost:

The maximum value that can be configured by default is63. If there is a requirement for a higher cost range, the metric-style can be changed towide, which allows the cost range to extend beyond 63.

Option A (67):Incorrect. 67 is not the maximum default value.

Option B (63):Correct. This is the maximum default cost value.

Option C (64):Incorrect. This is beyond the default range.

Option D (68):Incorrect. This is beyond the default range.

A is correct– Confederations arespecifically designed for large-scale BGP deploymentswhere a full IBGP mesh is impractical.

B is correct– Sub-ASs within a confederation establishEBGP-like connectionsbetween each other but behave like IBGP within the overall AS. These sub-ASsdo not require full-mesh inside the confederation, but EBGP rules are followed between sub-ASs.

C is false–Not all devices need to be reconfigured. Devices within the same sub-AS retain normal IBGP behavior and minimal changes.

D is correct– Confederation istransparent to external peers, so thelogical topology remains the samefrom outside the AS.

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

“BGP confederation divides an AS into multiple sub-ASs. EBGP-like sessions are established between sub-ASs, while reducing IBGP mesh complexity. The external AS still sees the AS as one unit.”

(Chapter: BGP Scalability Enhancements – Section: Confederation)

 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​​.

In inter-AC roaming scenarios, an AC (Access Controller) can serve as the mobility server for multiple mobility groups, enabling it to manage roaming among multiple groups. However, an AC can only belong to one specific mobility group. This constraint ensures that mobility management remains streamlined and avoids conflicts. Huawei WLAN mobility configuration guides validate this setup ​.

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 ​.

 BGP Keepalive Message Behavior

Keepalive messages are used to maintain the Established state of a BGP peer relationship.

The Keepalive timer determines the frequency of these messages and defaults to60 seconds, as per the BGP specification.

 HCIP-Datacom-Core Reference

The Keepalive timer default value is covered in the BGP configuration and operational principles​​.

Comprehensive and Detailed In-Depth Explanation:

TheFlag fieldin a routing table entry provides specific information about the route.

G (Gateway flag): This flag indicates that the next hop is agateway (another router)rather than a directly connected destination.

S (Static flag): This flag indicates that the route was manually configured as astatic route.

H (Host flag): This flag means that the destination is adirectly connected host, not a network.

D (Dynamic flag): This flag is used fordynamically learned routesfrom protocols like OSPF, EIGRP, or BGP.

Since we are looking for the flag that indicates thenext hop is a gateway, the correct answer isG.

????Reference:Huawei HCIA-Datacom Study Guide, Chapter on Routing Table and FIB Entries.

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.

 IS-IS Overview: Intermediate System to Intermediate System (IS-IS) is a link-state routing protocol. Routers exchangeLink State Packets (LSPs)to maintain a synchronized link-state database. These LSPs are categorized intoLevel-1 LSPs(intra-area routing) andLevel-2 LSPs(inter-area routing). Both types share the same packet format.

HCIP-Datacom-Core Technology Training Material (IS-IS LSPs and Packet Structure)​​.

 LSP ID Format: The LSP ID uniquely identifies each LSP and ensures accurate routing information. It comprises the following components:

System ID (C): A 6-byte identifier assigned to each router, derived from the router's NET (Network Entity Title). This identifier ensures unique identification of routers within the IS-IS domain.

Pseudonode ID (B): Assigned when a router acts as a Designated Intermediate System (DIS) on a broadcast network. It differentiates LSPs generated by the DIS from other routers.

LSP Number (A): A 1-byte field indicating the sequence number of the LSP. It helps distinguish multiple LSPs generated by the same router for the same level.

A is false– Thedefault value of Local_Pref is 100, not 0.

B is false–Local_Pref is not advertised to EBGP peers, it is only sent toIBGP peers.

C is correct– TheLocal_Pref value stays constantunless modified by a route-policy or filter.

D is correct–Higher Local_Pref values indicate preferred paths, so BGP prefers the path with the highest Local_Pref among multiple options.

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

“Local_Pref is used to select the best outbound path for traffic leaving the AS. It is only shared among IBGP peers and defaults to 100. The higher the value, the more preferred the route.”

(Chapter: BGP Path Attributes – Section: Local Preference)

The error indicates "Incorrect remote AS," which refers to a mismatch in the autonomous system (AS) numbers during BGP peer configuration. This issue is unrelated to the neighbor address. The neighbor address (10.1.1.5) and timestamp (2010-03-22 12:40:39) provided in the output are correct, and the error type confirms a neighbor relationship issue ​.

Routing Entries in PIM

(S, G) entries: Represent the shortest path tree (SPT) from a specific source (S) to a specific multicast group (G). These entries are created after data packets are transmitted directly from the source to the receivers.

(S, G) entries are used in both PIM-DM and PIM-SM modes.

PIM-DM and PIM-SM Modes

InPIM-DM, multicast traffic is initially flooded throughout the network and pruned where no receivers exist. (S, G) entries represent source-specific paths created after the flooding stage.

InPIM-SM, multicast traffic initially flows through a shared tree, but (S, G) entries are created when the network switches to the SPT for more efficient forwarding.

HCIP-Datacom-Core Reference

The functionality and application of (S, G) routing entries are detailed in multicast and PIM configuration 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 ​.

Routing policies are used to control how routes are imported, advertised, or received. Policy-Based Routing (PBR) is used to forward packets based on policies, bypassing the routing table. Routing policies are not used for packet forwarding ​.

BGP does not advertise all routes learned from peers to other peers. By default, only the best (optimal) routes selected by BGP are advertised to other peers. Additionally, routes learned from IBGP peers are not forwarded to other IBGP peers unless a route reflector or confederation setup is used. The statement claiming all learned routes are advertised is false ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of PBR (Policy-Based Routing):

Policy-Based Routing (PBR) allows you to override traditional routing decisions by defining user-specific policies.

Interface-Based PBR: Applied to packets arriving at a specific interface and affects traffic being forwarded through the device.

Local PBR: Applied to traffic generated by the local router itself (e.g., locally originated packets such as management traffic).

2. Analysis of Each Statement:

Option A: Interface-based PBR takes effect only for forwarded packets.

Correct (True Statement).

Interface-based PBR applies only to packets arriving at a specific interface and being forwarded through the router. It does not affect locally originated traffic.

Option B: Local PBR takes effect only for locally originated packets.

Correct (True Statement).

Local PBR specifically applies to traffic generated by the router itself, such as pings, SNMP requests, or routing protocol updates.

Option C: Interface-based PBR is configured on an interface and takes effect only for incoming packets on the interface.

Correct (True Statement).

Interface-based PBR is applied directly on the interface using commands like policy-based-route. It only affects traffic entering the specified interface.

Option D: Local PBR is configured in the protocol view.

Incorrect (False Statement).

Local PBR is not configured in the protocol view. It is typically configured using the command local-policy in the system view to handle traffic generated by the router.

3. Summary:

Correct Answer:D (Local PBR is NOT configured in the protocol view).

Huawei HCIA-Datacom Study Guide, Chapter "Policy-Based Routing."

Comprehensive and Detailed In-Depth Explanation:

InIS-IS, routes are distributed differently based onrouter levels:

Level-1 (L1) routers→ Maintainspecific routes only within their own area.

Level-2 (L2) routers→ Maintainspecific routes for the entire network(inter-area routing).

Level-1-2 (L1/L2) routers→ Storeboth L1 and L2 routesand act asarea border routers.

In the diagram,R2 and R3 are L1/L2 routers, meaning they storespecific routes for both their area and other areas.

R1 is only an L1 router, meaning it only hasintra-area routes, andR7 is an L2-only router, meaning it does not store all specific routes.

Therefore,R2 and R3havespecific routesfor the entire network.

????Reference:Huawei HCIA-Datacom Study Guide, IS-IS Routing Levels and Route Distribution.

Comprehensive and Detailed In-Depth Explanation:

Stub areasdo not allowexternal routes(Type 5 LSAs).

SinceASBRs are responsible for redistributing external routesinto OSPF, theycannot exist in a stub area.

If an ASBR were placed in a stub area, it would attempt to inject external routes into the OSPF domain, which contradicts the stub area rules.

To allow external routes,Not-So-Stubby Areas (NSSAs)are used instead, which allowASBRsand useType 7 LSAsto carry external routes.

????Reference:Huawei HCIA-Datacom Study Guide, OSPF Area Types and ASBR Restrictions.

In SNMP (Simple Network Management Protocol), the MIB (Management Information Base) defines the attributes of a managed device. It acts as a structured database of managed objects, each described by a unique OID (Object Identifier). These objects provide critical information and control interfaces for network management. Other elements like the agent (manages the MIB) and NMS (queries the agent) do not define attributes but interact with the MIB ​.

The operator betweenif-matchclauses under a node is AND, meaning all conditions must be satisfied. However, the operator between nodes is OR, meaning a route matching any node will pass the route-policy ​.

This statement isfalsebecauseIGMPv2 improves upon IGMPv1 by introducing the Leave Group message.

InIGMPv1, members leave silently, and the router waits for the timeout.

InIGMPv2, a host sends aLeave Groupmessage, prompting the router to send aGroup-Specific Queryto determine if other members are still present. If no responses are received, the group is pruned before timeout.

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

“IGMPv2 allows group members to actively send Leave messages, reducing unnecessary forwarding delays. This improves efficiency over IGMPv1.”

(Chapter: Multicast Protocols – Section: IGMP Versions)

Comprehensive and Detailed Step-by-Step Explanation:

BGP Router ID Selection Rules:

If a router ID is not manually configured:

The largest loopback address is selected as the router ID.

If no loopback interfaces exist, the largest active physical interface address is selected.

Default Behavior:

This ensures that a stable and unique router ID is chosen automatically, even without manual configuration.

In OSPF, DR and BDR listen on the multicast address 224.0.0.6, while all OSPF routers (including DR others) listen on 224.0.0.5. DR others establish neighbor relationships with DR and BDR, but they do not listen on 224.0.0.6. This makes Option D incorrect, as only DR and BDR use 224.0.0.6 ​.

The prefix list permits the prefix1.1.1.1/24with a mask length greater than or equal to/26and less than or equal to/32. This means only prefixes with the base1.1.1.1and mask lengths between/26and/32will be permitted. Routes like1.1.1.2/16and1.1.1.1/24do not meet the mask length criteria, so they will be denied. Conversely, routes like1.1.1.1/26and1.1.1.1/32satisfy the condition and will be permitted ​.

DIS Election in IS-IS:

In IS-IS, theDesignated Intermediate System (DIS)is elected on broadcast networks to reduce the number of LSAs exchanged and maintain the LSDB.

The DIS is elected based onpriority:

The router with thehighest priorityis elected as the DIS.

If priorities are equal, theSystem IDis used as a tie-breaker, and the router with thehighest System IDbecomes the DIS.

HCIP-Datacom-Core Technology Training Material (IS-IS DIS Election Mechanism)​​.

Given DIS Priorities:

R1: Priority = 10

R2: Priority = 20

R3: Priority = 30

R4: Priority = 40

R4 has the highest DIS priority of 40, which makes it the clear choice for DIS election.

Scenario Details:

Since all devices are started simultaneously, the DIS election process will follow the priorities without requiring a tie-breaker (System ID).

Conclusion:

The device with the highest DIS priority isR4, and it will be elected as the DIS.

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of BGP:

BGP (Border Gateway Protocol) is an Exterior Gateway Protocol (EGP) designed to exchange routing information between different Autonomous Systems (ASs) on the internet. Unlike traditional distance-vector protocols (like RIP), BGP is considered a path-vector protocol, as it not only determines reachability but also ensures policy-based routing decisions and advanced path selection mechanisms.

2. Analysis of Each Option:

Option A: BGP does not support authentication. Therefore, it cannot ensure network security.

This statement isincorrect.

BGP supports authentication using mechanisms such as TCP MD5 (Message Digest 5) and TCP-AO (Authentication Option). These authentication mechanisms ensure that BGP messages are not tampered with or intercepted during transmission, enhancing network security.

HCIA-Datacom Study Guide, Chapter "BGP Concepts and Features," Authentication Section.

Option B: BGP uses TCP as the transport layer protocol.

This statement iscorrect.

BGP relies on TCP (Transmission Control Protocol) as its transport layer protocol, specifically on port 179. TCP provides reliable delivery of BGP messages and ensures the session remains established in case of transient network issues.

TCP also handles error recovery and sequencing, making it a suitable choice for BGP, which requires reliable communication between peers.

Comprehensive and Detailed In-Depth Explanation:

NET (Network Entity Title)is a special form ofNSAP (Network Service Access Point)used inIS-IS routing.

NET consists of three fields:

AFI (Authority and Format Identifier) + IDI (Initial Domain Identifier) + Area Address→ Identifies thearea.

System ID→ Uniquely identifies arouter within an area(similar to an OSPF Router ID).

SEL (NSEL - N-selector)→ Always0in a NET, as IS-IS operates at Layer 3.

SinceSystem IDuniquely identifies ahost/router within an area, the correct answer isA.

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

 OSPF Area Design and Loop Prevention:

OSPF uses a hierarchical structure with areas to improve scalability and efficiency. Area 0, the backbone area, plays a crucial role in ensuring loop-free route distribution between areas. The following mechanisms are key to preventing routing loops:

Strict adherence to hierarchical area design.

Prohibition of direct inter-area route exchanges between non-backbone areas.

HCIP-Datacom-Core Technology Training Material (OSPF Basics and Advanced Concepts)​​.

 Analysis of Each Statement:

A. Inter-area routes cannot be directly transmitted between non-backbone areas.This statement isTRUE. OSPF mandates that all inter-area routing must pass through Area 0. Direct inter-area route exchanges between two non-backbone areas are not allowed to prevent loops.

Option B isfalse. By default, when the aggregate command is usedwithout any options, BGP generates asummary route, andsuppresses the specific routesthat fall under that summary. To advertise both specific and summary routes, you mustexplicitly configurethe detail-suppressed option to control whether specifics are suppressed or not.

Explanation of the other options:

Ais correct: When suppress-policy is specified, only specific routes matching the policy are advertised; others are suppressed.

Cis correct: The summary automatic command causes summarization based on classful boundaries, which is a legacy behavior.

Dis correct: With detail-suppressed, only the summary route is advertised, not specific prefixes.

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

“The aggregate command suppresses specific routes by default unless explicitly configured otherwise. Use of suppress-policy or detail-suppressed allows control over which routes are advertised.”

(Chapter: BGP Advanced Features – Section: Route Aggregation)

In the PIM protocol,Register StopandGraftmessages are sent with unicast destination addresses, typically to specific neighbors or RP (Rendezvous Point) routers. Other messages likeBootstrapandAssertuse multicast addresses for broader dissemination across the network ​.

The Local-Preference attribute is used within an AS to influence outbound traffic paths. The default value is 100, and it is a well-known discretionary attribute, meaning it is not mandatory and does not travel across AS boundaries ​.

An IP prefix filter is designed to match both the IP address and its prefix length, making it suitable for filtering routing information rather than data packets. Options A and D are incorrect because IP prefix filters do not work directly on data packets, and they can match both prefix numbers and lengths ​.

1. Understanding Prefix List Configuration:

The command ip ip-prefix huawei index 10 permit 10.1.1.0 24 greater-equal 26 defines a prefix filter:

The base prefix is 10.1.1.0/24.

The greater-equal 26 condition specifies that the mask length of matching prefixes must beat least 26 bits.

If the less-equal parameter is not explicitly defined, the default value is32, meaning the longest possible mask length for IPv4.

2. Explanation of Values:

greater-equal-value: Specifies the minimum mask length. In this case, the value is26.

less-equal-value: Specifies the maximum mask length. Since it is not explicitly configured, the default value is32.

3. Summary:

greater-equal-value = 26

less-equal-value = 32

Huawei HCIA-Datacom Study Guide, Chapter "IP Prefix List Configuration."

 Inasynchronous mode, BFD control packets are exchanged periodically to detect faults.

 Indemand mode, once the session is established, BFD stops sending periodic control packets and relies on external mechanisms to verify connectivity.

 Asynchronous mode is the most commonly used mode. However, the Echo function is supported in asynchronous mode, making Option B incorrect ​.

Comprehensive and Detailed In-Depth Explanation:

IP Multicast vs. Broadcast:

A. TRUE→ Unlikebroadcast, which sends data toall hostsin a subnet,multicast only sends data to interested receivers,preventing flooding.

B. TRUE→Multicast optimizes bandwidth usageby sending asingle copy of data, which is thenreplicated at network routers only when necessary.

IP Multicast vs. Unicast:

C. FALSE→Multicast does not improve security; it may expose data to unintended receivers ifnot properly controlled.

D. FALSE→Multicast reduces the load on the sourcebecause asingle data stream serves multiple receiversinstead of sendingindividual unicast streams.

????Reference:Huawei HCIA-Datacom Study Guide, IP Multicast Principles and Benefits.

BFD (Bidirectional Forwarding Detection)is a lightweight protocol that providesrapid detectionof faults in the forwarding path between two routers or switches.

It worksin conjunction with routing protocolsand provides fast failure detection to enable quick route convergence.

Protocol support:

B. BFD for static routes– Supported. BFD tracks the reachability of next-hop addresses and can trigger route removal upon failure.

C. BFD for OSPF– Supported. BFD can be associated with OSPF to accelerate the detection of neighbor failures.

D. BFD for BGP– Supported. BFD enables sub-second detection of BGP peer failures.

A. BFD for PIM–Not supported. PIM (Protocol Independent Multicast) typically does not use BFD for neighbor failure detection.

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

“BFD can be associated with static routes, OSPF, IS-IS, BGP, and other protocols to quickly detect link or device faults and trigger fast rerouting.”

(Chapter: High Availability Technologies – Section: BFD Principles and Applications)

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 ​.

After Layer 3 roaming, the STA’s traffic is forwarded from the Foreign AP (FAP) to the Foreign AC (FAC), and then to the Home AC (HAC) before reaching the upper-layer network. This ensures that the STA remains on the same subnet without breaking existing sessions ​.

 GMP Snooping Proxy

IGMP snooping proxy allows the switch to substitute for upstream Layer 3 devices and downstream hosts, reducing unnecessary bandwidth consumption by consolidating IGMP messages.

 HCIP-Datacom-Core Reference

The IGMP snooping proxy functionality is described in multicast optimization and IGMP configuration chapters​​

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 ​.

RSTP improves convergence by introducing changes to the BPDU handling mechanism and port roles. However, RSTP does not rely on a fixed timeout of four Hello intervals for negotiation failure. Instead, RSTP uses a more dynamic mechanism to detect topology changes. The other options describe valid RSTP improvements ​.

Comprehensive and Detailed Step-by-Step Explanation:

BGP Router ID Behavior:

The router ID uniquely identifies a BGP device in the network.

If the router ID is changed, it is equivalent to creating a new BGP instance, and the existing BGP session is reset to establish a new peer relationship.

Impact of Router ID Change:

BGP peering relies on stable identifiers. Changing the router ID disrupts the TCP session and requires reestablishing the relationship.

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.

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)

IGMP Version Mismatch

If the IGMP snooping version on the device is earlier than the IGMP version on user hosts, the device may fail to parse IGMP Report messages correctly. As a result, the device forwards these messages only to router ports without generating group member ports or forwarding entries.

Consequently, users cannot receive multicast data.

HCIP-Datacom-Core Reference

Multicast and IGMP snooping behaviors under mismatched conditions are described in the multicast configuration chapters​​.

 pat

 trust

 12.1.1.0

 inner

 ACL in Routing Policies

ACLs are frequently used in routing policies to match specific routes based on criteria such as source IP, destination IP, and more. This allows ACLs to influence route redistribution, filtering, and forwarding decisions.

 HCIP-Datacom-Core Reference

ACL applications in routing policies are discussed in the routing policy chapters​​.

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.

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

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)

Comprehensive and Detailed Step-by-Step Explanation:

IPv4 Address Classes:

Class D:Reserved for multicast and defined by the first four bits as1110.

Address range:224.0.0.0 to 239.255.255.255.

Structure:

Class D does not include a network/host division, as it is designed for group communication rather than device identification.

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

BGP (Border Gateway Protocol) uses specific message types to establish and maintain peer relationships between routers. The primary BGP messages involved during the establishment and maintenance of peer relationships are:

Open (D):

The Open message is the first message sent after a TCP connection is established between BGP peers.

It is used to exchange parameters such as the AS number, BGP version, hold time, and BGP identifier.

Keepalive (A):

After the Open message exchange, Keepalive messages are sent periodically to maintain the BGP session.

These messages confirm that the connection is still alive.

Update (C):

Update messages are used to exchange routing information after the peer relationship is established.

They contain information about network prefixes and their associated path attributes.

Hello (B):

Hello messages are not used in BGP. They are typically used in protocols like OSPF or IS-IS to establish and maintain neighbor relationships.

Thus, the correct answers areA (Keepalive),C (Update), andD (Open).

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.

 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.

 R3, as the DIS in the Level-2 domain, periodically sends Complete Sequence Number Protocol Data Units (CSNPs) to ensure LSDB synchronization among Level-2 routers.

 R1 and R2 are in a Level-1 domain, and IS-IS requires the receiving router (R2) to acknowledge an LSP from R1 by sending a Partial Sequence Number Protocol Data Unit (PSNP).

 IS-IS LSPs in a broadcast network are sent using multicast, not unicast, making option C incorrect.

 For Level-2 LSPs, acknowledgments are not provided using PSNP by R3; CSNPs are sufficient for synchronization ​.

 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:

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.

A stateful inspection firewall tracks the state of network connections and only matches the initial packet against its rule set. Subsequent packets in the same connection are matched in the state table. Contrary to this, UDP packets can be inspected by correlating them with connection states, and packets in a single connection are always correlated ​.

 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 ​.

 ACL Matching in Huawei Routers:

Access Control Lists (ACLs) are used to filter packets based on specific criteria, such as source/destination IP, ports, or protocols.

When a packet arrives, the Huawei router processes it against the configured ACL rules to decide whether to permit or deny the packet.

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 ​.

The route-policy configuration specifies that node 10 matches the IP prefix11.1.0.0/16and applies a cost of 300 to this route. Once a route matches a node, it is no longer processed by subsequent nodes, making option D incorrect. Option B is also incorrect because only specific matching routes have their costs changed ​.

VRRP defines the following states:Initialize– The router is starting up or has not joined a VRRP group.Backup– The router is in standby and monitors the Master.Master– Theonly statewhere the deviceforwards trafficfor thevirtual IP address.Only the router in theMasterstate owns the virtual MAC and responds to ARP for the virtual IP.Reference from Huawei HCIP-Datacom-Core Technology Study Guide:“In VRRP, only the Master forwards packets destined for the virtual IP address. Backup routers take over only if the Master fails.”(Chapter: VRRP Concepts – Section: State Roles and Transitions)

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding LSA Filtering in OSPF and IS-IS:

The filter-policy command is used in OSPF and IS-IS to control which routing information isimported into the local routing tableoradvertised to other neighbors.

However, itcannot filter LSAs forwarded by neighbors. In OSPF and IS-IS, LSAs are always forwarded unchanged within the area to ensure all routers have a consistent link-state database.

Filtering only affects the routes that are installed into the local routing table or advertised to other areas or neighbors.

2. Why the Statement is False:

LSAs are forwarded without being filtered. This ensures link-state protocols maintain the same network topology view across the network.

The filter-policy import command only controls routes that are installed into the local routing table, not the forwarding of LSAs.

3. Summary:

The statement is FALSE because LSAs cannot be filtered by filter-policy import.

Huawei HCIA-Datacom Study Guide, Chapter "OSPF Route Filtering."

RFC 2328: OSPF Version 2, LSA Propagation Rules.

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 Step-by-Step Explanation:

1. Understanding the Prefix List Configuration:

The command ip ip-prefix test index 10 permit 10.0.0.0 8 less-equal 32 defines the following:

The prefix base is 10.0.0.0 with a mask length of 8 bits.

The less-equal 32 condition allows routes with mask lengths ranging from 8 to 32 bits to match.

2. Analysis of Each Route:

Option A: 10.1.1.1/32

Correct.

The prefix 10.1.1.1/32 falls within the 10.0.0.0/8 network range and has a mask length of 32 bits, which satisfies the less-equal 32 condition.

Option B: 10.1.1.0/6

Incorrect.

The prefix 10.1.1.0/6 has a mask length of 6 bits, which is shorter than the base prefix length of 8. It does not satisfy the condition.

Option C: 10.1.1.0/24

Correct.

The prefix 10.1.1.0/24 falls within the 10.0.0.0/8 network range and has a mask length of 24 bits, which satisfies the less-equal 32 condition.

Option D: 10.0.0.0/16

Correct.

The prefix 10.0.0.0/16 falls within the 10.0.0.0/8 network range and has a mask length of 16 bits, which satisfies the less-equal 32 condition.

3. Summary:

The prefixes that match the configuration are 10.1.1.1/32, 10.1.1.0/24, and 10.0.0.0/16.

Huawei HCIA-Datacom Study Guide, Chapter "IP Prefix Lists."

Huawei Configuration Examples for ACL and Prefix Lists.

In the given topology, the route from R4 to 10.0.2.2/32 traverses R3, which performs route leaking from Level-2 to Level-1. The cost is calculated as follows: R4 to R3 (40) + R3 to R2 (10) + R2 to the destination (30), resulting in a total cost of 80 ​.

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:

1. Port Priority in RSTP:

RSTP (Rapid Spanning Tree Protocol) elects root and designated ports based on port priority and port ID.

Port priority is a configurable value that helps determine which port becomes the root or designated port when multiple ports are eligible.

The port ID consists of the port priority and port number. When priorities are equal, the port number is used as a tiebreaker.

2. Default Port Priority on Huawei Switches:

On Huawei switches, the default port priority is128.

This value can be adjusted in increments of 16 using the command stp port priority.

3. Analysis of Options:

Option A: 1

Incorrect. This is not the default port priority value.

Option B: 128

Correct. This is the default port priority value on Huawei switches.

Option C: 4096

Incorrect. This is not a valid default port priority value.

Option D: 32768

Incorrect. This is the default bridge priority, not the port priority.

4. Summary:

The default port priority on Huawei switches is128.

Huawei HCIA-Datacom Study Guide, Chapter "RSTP Port Role Election."

IEEE 802.1D-2004: Rapid Spanning Tree Protocol (RSTP).

Root protection ensures that a designated port does not become a root port by discarding superior BPDUs. However, if superior BPDUs are no longer received, the port can return to its original forwarding state, meaning its role can change. This makes option B incorrect, while the other options correctly describe RSTP behavior ​.

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 ​.

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 ​.

 Understanding Router ID and Its Role in OSPF:

In OSPF, the Router ID uniquely identifies a router within the OSPF domain. If two routers are configured with the same Router ID, it can lead to issues such as LSA conflicts and flapping. This is because the Router ID is used as a key in OSPF operations, including LSA generation and database synchronization.

HCIP-Datacom-Core Technology Training Material (OSPF Basics - Router ID and LSA Handling)​.

 Scenario Details:

Different Areas: Even if the two routers belong to different areas, the Router ID remains globally significant in the OSPF domain. This means that any duplication of Router IDs will confuse OSPF mechanisms.

ASBR (Autonomous System Boundary Router): When one of the routers is an ASBR, it generates Type 4 and Type 5 LSAs to describe external routes. These LSAs use the Router ID asan identifier. If another router in the network has the same Router ID, conflicts occur during LSDB synchronization.

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:

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.

In BGP and other TCP-based protocols like OSPF and IS-IS, when devices havedifferent Hold Times, thesmaller value is chosenafter negotiation. This ensuresfaster detectionof communication loss.

The Keepalive and Hold Timers are negotiated during the establishment of a BGP session.

The smaller Hold Timeis used to maintain symmetry and prevent timeouts.

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

“When negotiating Hold Time, both ends agree to use the smaller of the two values. This value is used to detect failures faster.”

(Chapter: BGP Fundamentals – Section: BGP Session Establishment)

Comprehensive and Detailed Step-by-Step Explanation:

1. Features of Wi-Fi 6:

Wi-Fi 6 (802.11ax) introduces several new technologies to improve network efficiency, reduce latency, and optimize power usage:

OFDMA (Orthogonal Frequency Division Multiple Access):Allows multiple devices to transmit simultaneously, improving concurrency.

TWT (Target Wake Time):Reduces power consumption by scheduling communication times for devices.

High Bandwidth:Supports up to 9.6 Gbps, significantly faster than Wi-Fi 5.

2. Why Zero Latency is Incorrect:

While Wi-Fi 6 reduces latency compared to earlier standards,zero latencyis not achievable due to inherent delays in network communication.

The statement "Realizes zero latency" is misleading and technically inaccurate.

3. Analysis of Each Option:

Option A: Uses OFDMA technology to achieve high concurrency.

Correct (True Statement).

OFDMA is a core feature of Wi-Fi 6 that improves concurrent communication.

Option B: Realizes zero latency, ensuring efficient service running.

Incorrect (False Statement).

Wi-Fi 6 reduces latency but cannot eliminate it entirely.

Option C: Provides high bandwidth, up to 9.6 Gbps.

Correct (True Statement).

Wi-Fi 6 supports a theoretical maximum bandwidth of 9.6 Gbps.

Option D: Uses TWT technology to reduce terminal power consumption.

Correct (True Statement).

TWT schedules communication times, allowing devices to enter low-power states and conserve battery life.

4. Summary:

Thefalsestatement isB, as Wi-Fi 6 does not achieve zero latency.

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.

Attributes such ascommunity,tag, andorigincan be directly referenced in theapplyclause of a route-policy. However,IP-prefixis not an attribute but a prefix list used for matching, and it cannot be directly applied ​.

TheDHCPNAKmessage is sent by the DHCP server to the client to indicate that the requested configuration is not valid. Messages likeDHCPDiscover,DHCPRequest, andDHCPReleaseare initiated by the client in the DHCP process ​.

Comprehensive and Detailed In-Depth Explanation:

STP (Spanning Tree Protocol) BPDUsdo not contain an explicitport role field. Instead, roles are determined indirectly.

RSTP (Rapid Spanning Tree Protocol)modifies BPDU structureby using theFlags fieldto indicate:

Port roles (Root, Designated, Alternate, Backup)

Proposal/Agreement (P/A) handshake mechanism

The correct field thatspecifies the port role in RSTP BPDUsisFlags.

????Reference:Huawei HCIA-Datacom Study Guide, RSTP BPDU Structure and Flags Field.

 Additional Port Roles in MSTP

Master Port: Indicates the port on the shortest path to the root bridge in a region.

Regional Edge Port: Identifies a port at the boundary of the MST region.

Backup and edge ports exist in RSTP and are not newly introduced by MSTP.

 HCIP-Datacom-Core Reference

MSTP port roles are elaborated in the MSTP configuration sections​​.

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:

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.

Internet– Thiscommunity 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 toanypeer.

No_Export– Prevents the route from being advertised toEBGP peers.

No_Export_Subconfed– Restricts the route from being advertisedoutside the sub-ASin 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)