H12-821_V1.0 HCIP-Datacom-Core Technology V1.0 Questions and Answers

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

Root Bridge ID – Identifies the current root bridge.

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

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

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

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

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

In a stateful inspection firewall, if the status detection mechanism is enabled, it tracks and validates the state of connections using the session table. If there is no session table and a SYN+ACK packet reaches the firewall, it checks the security policy. If the policy explicitly permits the packet, it will pass through the firewall, but no session table will be created without the initial SYN packet. The other options are either incorrect or misrepresent the behavior of stateful inspection ​.

Option B is false . By default, when the aggregate command is used without any options , BGP generates a summary route , and suppresses the specific routes that fall under that summary. To advertise both specific and summary routes, you must explicitly configure the detail-suppressed option to control whether specifics are suppressed or not.

Explanation of the other options:

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

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

D is 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)

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 ​.

The Origin attribute in the display bgp routing-table output is marked as i , indicating that the route was injected into the BGP routing table using the network command. The other options are incorrect because the AS path is not displayed, the MED is 0 , and the route is marked as the best ( > ), meaning it is the optimal route ​.

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 ​.

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 is one-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.

Comprehensive and Detailed In-Depth Explanation:

A. TRUE → The interface GigabitEthernet0/0/1 has an IP address of 192.168.1.1 .

B. TRUE → The IGMP version is explicitly stated as IGMPv2 .

C. TRUE → The maximum query response time for IGMP is set to 10 seconds .

D. TRUE → The IGMP Query Interval is configured as 60 seconds , meaning the router sends Group-Specific Queries every 60 seconds .

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

Comprehensive and Detailed In-Depth Explanation:

SNMP (Simple Network Management Protocol) v3 is a more secure version of SNMP, supporting authentication and encryption .

If the NMS is not receiving SNMPv3 traps , possible causes include:

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

B. TRUE → If the SNMPv3 password is incorrect , authentication will fail, and traps will not be processed by the NMS.

C. FALSE → The size of packets sent by the NMS does not affect incoming SNMP traps from the router.

D. TRUE → The community name must match on both the NMS and the router , or traps will be ignored.

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

Comprehensive and Detailed Step-by-Step Explanation:

1. Single-Hop BFD Session:

A single-hop BFD session is used to detect link failures between directly connected devices.

It is bound to the local IP address and the peer IP address , and the session relies on these parameters to establish connectivity.

2. Why Modifications Require Deletion:

BFD sessions are tightly bound to their configuration parameters (e.g., local and peer IP addresses).

Modifying these parameters is not supported for an existing session. Instead, you must delete the session and recreate it with the updated parameters.

3. Why the Statement is TRUE:

The statement correctly describes the behavior of BFD sessions, where modifying an existing session is not possible without deleting it first.

In asynchronous mode, two devices exchange BFD Control packets to monitor connectivity. However, this mode does support the echo function, which tests bidirectional paths by sending packets that loop back to the origin. This statement is incorrect. Demand mode, on the other hand, minimizes the control packet exchange, relying on periodic echo packets if configured. Huawei ' s BFD configuration guides emphasize these distinctions ​.

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 ​.

Understanding the LSDB and Level-2 DIS Election in IS-IS :

In IS-IS, the Designated Intermediate System (DIS) is elected for both Level-1 and Level-2 on broadcast networks to manage the link-state database (LSDB) and reduce the number of LSAs exchanged.

The election of the DIS is based on the highest priority . If the priority is the same, the router with the highest System ID becomes the DIS.

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 In-Depth Explanation:

Neighbor Discovery Protocol (NDP) replaces ARP in IPv6 and uses ICMPv6 messages for:

Router Solicitation (RS) → Sent by hosts to request Router Advertisement (RA) messages .

Router Advertisement (RA) → Sent by routers to announce prefixes and network parameters.

Neighbor Solicitation (NS) → Used for address resolution and Duplicate Address Detection (DAD) .

Neighbor Advertisement (NA) → Sent in response to NS messages .

Redirect → Used by routers to redirect hosts to better gateways .

RS is not directly used for address resolution ; Neighbor Solicitation (NS) does this , so the answer should be D .

???? Reference: Huawei HCIA-Datacom Study Guide, NDP and ICMPv6 Packet Types.

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.

Comprehensive and Detailed In-Depth Explanation:

SSH (Secure Shell) provides secure remote login and data encryption over insecure networks.

A. TRUE → SSH requires user authentication before access is granted.

B. TRUE → Enabling SSH opens listening ports , which could be scanned by attackers . Proper security measures (e.g., disabling unused SSH access) are recommended.

C. TRUE → ACLs can be applied to VTY (Virtual Terminal) lines to restrict SSH access based on IP addresses .

D. FALSE → The default SSH server port is 22, not 23 . Port 23 is used for Telnet , which is less secure than SSH.

???? Reference: Huawei HCIA-Datacom Study Guide, SSH Configuration and Security Measures.

Comprehensive and Detailed Step-by-Step Explanation:

Route Policy Overview:

A route-policy is a policy-based routing tool that filters and modifies routing information.

It consists of one or more nodes , and each node can specify match conditions and apply actions to routes.

Maximum Number of Nodes:

The maximum number of nodes supported in a route-policy is 1024 , allowing flexibility in route filtering and control.

In an OSPF broadcast or NBMA network with at least two routers, one router must act as the DR (Designated Router), and another as the BDR (Backup Designated Router) to ensure efficient communication and reduce the number of adjacencies. This is a requirement for OSPF operation in such network types ​.

In BGP and other TCP-based protocols like OSPF and IS-IS, when devices have different Hold Times , the smaller value is chosen after negotiation. This ensures faster detection of communication loss.

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

The smaller Hold Time is 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:

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.

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.

Comprehensive and Detailed Step-by-Step Explanation:

Interface ID in IPv6:

The interface ID is the last 64 bits of an IPv6 address, and it uniquely identifies an interface within a subnet.

It can be generated in three ways:

Manually Configured: Explicitly assigned by an administrator.

System-Generated: The operating system assigns a random or pseudo-random value.

EUI-64 Standard: Generated based on the MAC address of the interface.

Correct Statement:

IPv6 supports all three methods for generating interface IDs.

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

To answer this question, it is essential to distinguish between the roles of ABRs and ASBRs in OSPF and the function of route summarization:

Route Summarization on ABRs:

Route summarization in OSPF can reduce the number of inter-area Type 3 LSAs that ABRs propagate between areas.

ABRs perform route summarization to reduce the amount of routing information exchanged between areas, thereby decreasing the size of the routing table and improving resource utilization.

Route Summarization on ASBRs:

ASBRs summarize external routes (from outside OSPF) into Type 5 LSAs or Type 7 LSAs (in NSSAs).

ASBR route summarization does not impact inter-area Type 3 LSAs because ASBRs are responsible for importing and summarizing external routes , not summarizing routes between OSPF areas.

Since the statement refers to configuring route summarization on ASBRs to reduce inter-area Type 3 LSAs , it is incorrect . Route summarization for inter-area Type 3 LSAs must be configured on ABRs, not ASBRs.

Correct Statement: Route summarization on ABRs reduces the number of inter-area Type 3 LSAs.

In dual-link MSB networking with load balancing, the new AP will connect to the AC with the lower number of connected APs. In this case, AC2 has only 20 connected APs, while AC1 has 100. Therefore, the new AP will connect to AC2 ​.

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

In the topology, SWB ' s GE0/0/2 is the Root Port because it has the least cost path to the Root Bridge (SWA). SWC ' s GE0/0/1 is the Designated Port because it forwards traffic to SWA while maintaining the shortest path to the Root Bridge. This setup ensures efficient traffic flow in the spanning tree topology ​.

The filter-policy command 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 ​.

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

R1 imports the direct route 10.1.1.0/24 into OSPF .

This route is advertised by R1 to R2 and R3 via OSPF .

Both R2 and R3 are running IS-IS , and bidirectional route redistribution is configured between OSPF and IS-IS.

R2 and R3 both re-advertise the OSPF-learned route into IS-IS and then potentially re-learn it back from the IS-IS domain, causing redistribution loops unless properly controlled.

Now, the question focuses on R3’s routing table :

R3 already learns the route directly via OSPF from R1.

It also learns the same route again via IS-IS from 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 In-Depth Explanation:

AS_Path is a well-known mandatory attribute (not discretionary).

AS_Path characteristics :

A. TRUE → When advertising to IBGP peers, AS_Path remains unchanged to prevent routing loops.

B. TRUE → BGP uses AS_Path to detect loops (if a router sees its own AS in the path, it rejects the route).

C. FALSE → AS_Path is well-known mandatory, not discretionary .

D. TRUE → BGP ignores AS_Confed_Sequence and AS_Confed_Set when calculating the AS_Path length.

???? Reference: Huawei HCIA-Datacom Study Guide, BGP Path Attributes and Loop Prevention.

Mandatory BGP Attributes

Next_Hop : Specifies the next hop to reach the destination.

AS_Path : Lists the autonomous systems traversed, crucial for loop prevention and route selection.

Optional Attributes

MED (Multi-Exit Discriminator) and Local_Preference are optional attributes that aid in route preference but are not mandatory.

HCIP-Datacom-Core Reference

BGP attribute behavior and classifications are detailed in BGP path selection principles​​.

Comprehensive and Detailed Step-by-Step Explanation:

Analysis of the OSPF Neighbor State:

Router ID 10.0.5.5:

On interface 10.0.235.2 (GigabitEthernet0/0/1), the neighbor state is Full, indicating that adjacency is established.

The Designated Router (DR) is 10.0.235.5, which is the same as the neighbor ' s address.

Router ID 10.0.4.4:

On interface 10.0.24.2 (Serial1/0/1), the neighbor state is also Full, meaning adjacency is established.

The DR/BDR election status shows None, indicating that the interface is on a point-to-point link where DR/BDR election does not apply.

Validation of Each Option:

Option A: Correct. The DR IP address is explicitly shown as 10.0.235.5.

Option B: Correct. The neighbor state for both 10.0.5.5 and 10.0.4.4 is Full, confirming adjacency is established.

Option C: Incorrect. DR/BDR elections are irrelevant on point-to-point links like Serial1/0/1.

Option D: Correct. The Router IDs of R2 ' s neighbors are explicitly listed as 10.0.5.5 and 10.0.4.4.

The hardware modules of Huawei modular devices and their functions are:

Main Processing Unit (MPU): Provides control and management planes for the entire system, responsible for protocol processing, system security, and software upgrades.

Switch Fabric Unit (SFU): Provides the data plane, enabling high-speed data switching between service modules.

Line Processing Unit (LPU): Manages data forwarding, offering various interfaces (optical and electrical) for data access​​.

The prefix list permits the prefix 1.1.1.1/24 with a mask length greater than or equal to /26 and less than or equal to /32 . This means only prefixes with the base 1.1.1.1 and mask lengths between /26 and /32 will be permitted. Routes like 1.1.1.2/16 and 1.1.1.1/24 do not meet the mask length criteria, so they will be denied. Conversely, routes like 1.1.1.1/26 and 1.1.1.1/32 satisfy the condition and will be permitted ​.

Comprehensive and Detailed In-Depth Explanation:

Type 1 LSAs (Router LSAs) are generated by every OSPF router to describe its directly connected links and their states.

The Router ID (RID) must be unique in an OSPF domain; otherwise, OSPF calculations will fail due to ambiguous paths .

If two routers in the same area have the same Router ID , OSPF will fail to calculate Shortest Path First (SPF) correctly, leading to routing inconsistencies.

To prevent this, Huawei routers automatically detect duplicate Router IDs and prevent OSPF from functioning properly until the issue is resolved.

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

DIS Election in IS-IS :

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

The DIS is elected based on priority :

The router with the highest priority is elected as the DIS.

If priorities are equal, the System ID is used as a tie-breaker, and the router with the highest System ID becomes the DIS.

 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 ​.

A stateful inspection firewall tracks the state of active connections. If a packet matches an existing session in the firewall ' s state table, it is allowed to pass. The diagram indicates that the TCP packet matches the session state, so the firewall forwards it ​.

Comprehensive and Detailed In-Depth Explanation:

Router LSAs (Type 1 LSAs) are generated by every OSPF router to describe its directly connected links and their states.

The E (External) bit in the Options field of a Type 1 LSA indicates whether the router is acting as an Autonomous System Boundary Router (ASBR) .

If E = 1 , it means that the router is an ASBR , which means it is redistributing external routes (e.g., BGP, static routes) into OSPF.

IR (Internal Router) , ABR (Area Border Router) , and DR (Designated Router) do not set the E-bit in their Router LSA unless they are also ASBRs.

???? Reference: Huawei HCIA-Datacom Study Guide, OSPF Router Types and LSA Options.

In RSTP, a port in the discarding state neither forwards data frames nor learns MAC addresses. A port in the learning state does not forward data frames but starts learning MAC addresses. Therefore, options A and B are correct, while C and D are incorrect due to misunderstandings of these states ​.

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

BGP confederations are used to reduce the complexity of IBGP full-mesh connections within a large AS by dividing the AS into multiple sub-ASs (called " member ASs " ) while still appearing as a single AS to external ASs. Below is an analysis of each option:

A. The ASs outside a confederation still consider the confederation as one AS:

This is true. Externally, the entire confederation is seen as a single AS, identified by the main AS number.

B. After a confederation is configured, the original IBGP attributes can be retained:

This is true. The configuration of a confederation does not affect the IBGP attributes exchanged between routers.

C. After a confederation is configured, the original AS number is used as the confederation ID of each router:

This is true. The main AS number is used as the Confederation Identifier for all member ASs in the confederation.

D. A confederation divides an AS into several sub-ASs, and EBGP full-mesh connections are established in each sub-AS:

This is false. Within each sub-AS of a confederation, IBGP connections are still used (not EBGP). Confederations are designed to reduce the number of IBGP full-mesh connections required within a large AS by creating smaller, manageable sub-ASs.

Therefore, the correct answer is D.

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.

An OSPF AS-external LSA is used to describe routes to networks that are external to the OSPF Autonomous System (AS). This external route information is typically imported into OSPF by an Autonomous System Boundary Router (ASBR) .

If the Forwarding Address field in the AS-external LSA is set to 0.0.0.0, this indicates that traffic destined for the external network should be forwarded directly to the ASBR that advertised the external route.

The specific context mentioned here relates to the Not-So-Stubby Area (NSSA) , a type of OSPF area designed to handle AS-external routes in a more controlled way. In NSSAs:

Type 7 LSAs are used to describe AS-external routes.

The ASBR within the NSSA converts the Type 7 LSA to a Type 5 LSA before advertising it to the backbone area.

Hence, the correct acronym for the described functionality is NSSA .

Comprehensive and Detailed Step-by-Step Explanation:

OSPF State Machine:

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

The 2-Way state indicates 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 Step-by-Step Explanation:

Distance-Vector Protocols:

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

Example: RIP is a distance-vector protocol.

Link-State Protocols:

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

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

Border Gateway Protocol (BGP):

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

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 is B , as setting the BFD packet interval to the minimum can destabilize the network.

Secure access channels include protocols that encrypt the transmitted data to protect against interception or unauthorized access. HTTPS (HyperText Transfer Protocol Secure) ensures data encryption over web communications, while SFTP (Secure File Transfer Protocol) provides secure file transfer by utilizing SSH for data encryption. Telnet and SNMPv2, on the other hand, lack robust encryption and are considered insecure. Huawei security standards highlight the importance of encrypted communication to prevent data leaks ​.

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 ​.

 RST BPDU Handling

On an RSTP network, if a port receives an RST BPDU and determines its own buffered BPDU is superior, it discards the received BPDU without responding. This ensures stability and proper convergence in the network.

 HCIP-Datacom-Core Reference

BPDU handling is described in the RSTP operation chapters​​.

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 ​.

A pseudonode in IS-IS is a logical representation of a broadcast network segment (e.g., Ethernet) where the Designated 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 contained in LSPs generated by pseudonodes because routing information is advertised in the LSPs 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)

The silent-interface command 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 ​.

 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.

1 → A Startup message with a priority of 255 is received.

2 → A Startup message with a priority less than 255 is received.

3 → A Shutdown message is received.

4 → The Master_Down timer expires, an Advertisement packet with the priority of 0 is received, or a packet with a priority lower than the local priority is received.

5 → A packet with a priority higher than the local priority is received.

6 → A Shutdown message is received.

???? Reference: Huawei HCIA-Datacom Study Guide, VRRP Status Transitions.

Comprehensive and Detailed Step-by-Step Explanation:

1. IPv6 and Neighbor Discovery Protocol (NDP):

In IPv4, a host uses ARP (Address Resolution Protocol) to map an IP address to a MAC address for communication.

In IPv6, ARP is not used . Instead, IPv6 uses the Neighbor Discovery Protocol (NDP) for address resolution.

2. Why the Statement is FALSE:

IPv6 does not use ARP for resolving link-layer addresses.

IPv6 uses NDP, which operates through ICMPv6 messages to perform the equivalent function.

3. Summary:

The statement is FALSE because IPv6 uses NDP, not ARP, to obtain the link-layer address of the destination host.

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 ​.

OSPF (Open Shortest Path First) mandates that the backbone area (Area 0) serves as the central area for routing information exchange. To avoid inter-area routing loops, routing information is only exchanged between the backbone area and non-backbone areas, not directly between two non-backbone areas. Consequently, each Area Border Router (ABR) must connect to the backbone area to facilitate this routing exchange ​.

In asynchronous mode, 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 being demand mode ​.

In the provided configuration, IS-IS is enabled on Loopback0 but not on Loopback3 of R2. As a result, R2 will advertise the route 10.0.2.2/32 (from Loopback0 ) to R1 through IS-IS. However, the route 10.0.2.3/32 will not be advertised because IS-IS is not enabled on that loopback interface. The import-route direct command does not override this behavior ​.

Comprehensive and Detailed In-Depth Explanation:

Spanning Tree Protocol (STP) has long convergence times due to Listening and Learning states .

Rapid Spanning Tree Protocol (RSTP) introduces:

Proposal/Agreement (P/A) mechanism → Allows ports to quickly transition to Forwarding state without waiting.

This mechanism significantly reduces convergence time in a switched network .

Since RSTP does use the P/A mechanism to accelerate port forwarding, the statement is true .

???? Reference: Huawei HCIA-Datacom Study Guide, STP vs. RSTP and P/A Mechanism.

 Understanding BGP Route Summarization :

In Border Gateway Protocol (BGP), route summarization is 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.

Comprehensive and Detailed In-Depth Explanation:

STP Port Roles :

Root Port (RP) → Connects directly to the Root Bridge .

Designated Port (DP) → Forwards traffic for a given segment.

RSTP introduces two additional roles to improve redundancy:

Backup Port → A redundant Designated Port (on the same switch).

Alternate Port → A backup Root Port (path to the Root Bridge).

All four roles exist in RSTP , making the correct answer A, B, C, D .

???? Reference: Huawei HCIA-Datacom Study Guide, RSTP Port Roles and Rapid Convergence.

 IP Prefix List Matching Conditions

An IP prefix list matches based on:

Mask : Specifies the subnet mask length.

Action : Specifies whether to permit or deny.

Index : Orders the rules within the prefix list.

Port numbers are not applicable as matching conditions in an IP prefix list.

 HCIP-Datacom-Core Reference

IP prefix list configurations are detailed in the routing policy and route filtering chapters​​.

Policy-Based Routing (PBR) on interfaces is used to forward traffic based on specific policies rather than the routing table. However, PBR is not suitable for modifying the next-hop of locally originated traffic. Other scenarios listed are typical use cases for interface PBR ​.

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 over TCP for 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.

Comprehensive and Detailed In-Depth Explanation:

OSPF uses Hello packets to establish and maintain neighbor relationships. The method of sending Hello packets depends on the network type :

Broadcast networks (e.g., Ethernet) use multicast (224.0.0.5) to discover and maintain OSPF neighbors.

Point-to-Point (P2P) networks (e.g., PPP links) also use multicast (224.0.0.5) for Hello packet exchange.

Non-Broadcast Multi-Access (NBMA) networks (e.g., Frame Relay) require manual neighbor configuration and use unicast Hello packets instead of multicast.

Point-to-Multipoint (P2MP) networks can send Hello packets either unicast or multicast , but it depends on configuration.

???? Reference: Huawei HCIA-Datacom Study Guide, OSPF Neighbor Discovery and Hello Packet Mechanism.

LS Ack (Link State Acknowledgment) packets are used to acknowledge received LSAs and do not contain complete LSA information. Instead, they contain only the headers of LSAs being acknowledged. This contrasts with LS Update packets, which carry full LSA details. The misunderstanding of LS Ack functionality makes this statement false ​.

 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.

 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​​.

The command output indicates that the OSPF neighbor state is Full and that the neighbor relationship has been established. The statement confirms that the negotiation process during the exchange of DD (Database Description) packets has determined the role of the router, with the local device becoming the slave in the Master-Slave relationship, which is critical for LSA synchronization. The other options do not align with the output or OSPF principles ​

 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​​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is First-Time Authentication in SSH?

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

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

2. Process Explanation:

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

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

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

3. Why the Statement is TRUE:

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

Comprehensive and Detailed Step-by-Step Explanation:

IPv4 Address Classes:

Class D: Reserved for multicast and defined by the first four bits as 1110 .

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.

 IPv6 Address Behavior

Manually configured link-local addresses do not have a higher priority than 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​​.

The election of a Designated Router (DR) and Backup Designated Router (BDR) occurs during the OSPF network ' s initial setup or upon the failure of an existing DR. A new router joining an OSPF network does not automatically preempt the current DR, even if it has the highest priority. DR and BDR elections are not preemptive. The other statements are correct regarding OSPF DR/BDR election processes ​.

When two BGP peers negotiate the Hold Time, the shorter value between the two configured Hold Time values is selected. This ensures compatibility and maintains the stability of the BGP session ​.

Comprehensive and Detailed Step-by-Step Explanation:

WAN Definition:

A WAN is a large-scale network spanning a wide geographical area, connecting smaller networks such as LANs and MANs.

Use Cases:

WANs are commonly used for interconnecting campus networks, branch offices, and data centers over long distances.

Correct Statement:

The statement accurately describes the purpose and scope of WANs.

Comprehensive and Detailed In-Depth Explanation:

A. TRUE → EBGP-learned routes can be advertised to both IBGP and EBGP peers .

B. FALSE → BGP uses incremental updates , meaning it only advertises changed routes , not all routes.

C. TRUE → BGP advertises only the best path to prevent unnecessary routing information.

D. TRUE → IBGP split-horizon rule : Routes learned from IBGP peers are not re-advertised to other IBGP peers (to prevent loops).

???? Reference: Huawei HCIA-Datacom Study Guide, BGP Route Advertisement and Split-Horizon Rule.

Comprehensive and Detailed Step-by-Step Explanation:

1. How Firewalls Match Security Policies:

Firewalls use security policies to define rules for filtering traffic.

Each policy contains matching conditions (e.g., source IP, destination IP, protocol, etc.) and an action (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 logically ORed , 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 are B and D .

For first-time configuration of a newly purchased network device, administrators typically use the console port. This direct connection is secure and independent of network configuration, making it suitable for initial setups. Telnet, SNMP, or FTP require prior IP configuration, which is not feasible during the initial setup phase ​.

Comprehensive and Detailed Step-by-Step Explanation:

IS-IS Three-Way Handshake:

IS-IS uses a three-way handshake to establish neighbor relationships.

This process is applied on both point-to-point (P2P) and broadcast network 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.

Attributes such as community , tag , and origin can be directly referenced in the apply clause of a route-policy. However, IP-prefix is not an attribute but a prefix list used for matching, and it cannot be directly applied ​.

The command output confirms that the VLANs with IDs 2 and 4 are part of the VLAN pool named " STA. " The VLAN pool concept is used to allocate VLANs dynamically to devices or subnets, which reduces broadcast domain size and improves network efficiency. The total number of VLAN pools is unrelated to this output, and the assignment algorithm (hash or even) is not explicitly mentioned in the output. Huawei VLAN pool management references align with this analysis ​.

1 – Idle

2 – Connect

3 – OpenSent

4 – OpenConfirm

5 – Established

6 – Active

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

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

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

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

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

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

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

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

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

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

Access Control Lists (ACLs) can be classified into several types, including Basic ACL (filters based on source IP), Advanced ACL (filters based on multiple parameters like source and destination IP, protocol, and ports), and Layer 2 ACL (filters based on MAC addresses). User-defined ACLs are not a standard classification ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Multicast Applications:

Multicast is ideal for applications where data is sent from one source to multiple receivers, such as:

Real-Time Audio Conferencing: Multicast delivers audio streams to participants without duplicating the same data for each receiver.

Livestreaming: Streaming live events to viewers using multicast minimizes bandwidth usage by delivering a single stream to multiple users.

Network TV: Multicast is used in IPTV to broadcast TV channels efficiently.

2. Why Data Warehouse is Incorrect:

Data warehouse does not involve point-to-multipoint transmission. Data warehouse activities (e.g., analytics or database queries) typically use unicast connections for communication between the server and the client.

3. Summary:

The correct options are A, B, C , as they all involve point-to-multipoint communication supported by multicast.

The default STP priority on Huawei switches (and in the IEEE standard) is 32768 .

Lower priority values increase the likelihood of a switch becoming the root bridge. You can configure this value in increments of 4096.

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

“The default bridge priority of Huawei switches is 32768. The root bridge is elected based on the lowest bridge ID, which consists of the priority and MAC address.”

(Chapter: Spanning Tree Protocols – Section: RSTP and Bridge Election)

Based on the MSTP configuration shown, the role of the switch in MSTI 1 cannot be determined without additional details about the topology or priority values of other switches in the instance. The role could be a root switch, secondary root, or non-root, depending on these factors ​.

The summary automatic command 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 ​.

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 on different network segments and have different subnet masks , one solution is to change the OSPF network type to Point-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 is A. Point-to-point.

The asbr-summary command is executed in the global OSPF view to summarize external routes. The abr-summary command is executed in the OSPF area view to summarize routes between areas. By default, the advertise parameter is enabled unless explicitly overridden by the not-advertise option ​.

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 ​.

IGP routes can be injected into BGP using multiple methods, not just the network command. The import-route command can also be used to redistribute IGP routes into BGP. The network command requires the route to exist in the routing table, while import-route allows direct redistribution ​.

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 a later version of IGMP is backward-compatible and can identify Report messages from earlier versions.

However, a device running an earlier version of 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 the same as or later than the 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.

 BGP Open Message Components

The Open message contains the following critical parameters:

Local AS Number : The autonomous system of the router.

Router ID : A unique identifier for the router.

Hold Time : The maximum time the router will wait for Keepalive or other messages from its peer.

 Incorrect Option

C. NLRI : Network Layer Reachability Information is not included in Open messages; it is carried in Update messages.

 HCIP-Datacom-Core Reference

The structure and contents of Open messages are explained in BGP protocol details​​.

In IPv6 , fragmentation is handled only at the source node . Intermediate routers do not fragment packets . Instead, if a packet is too large for the next link, the router sends back an ICMPv6 Packet Too Big message 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)

Master

Backup

Master

Backup

A Totally Stubby Area in OSPF is a special type of stub area where only intra-area (Type 1) LSAs , router LSAs , and default routes (Type 3 LSA with 0.0.0.0/0) are allowed to be injected. It blocks inter-area routes (Type 3 LSAs for specific prefixes) and Type 5 LSAs (external routes) to reduce the size of the Link-State Database (LSDB) and enhance router performance.

Explanation of the Options:

A. Type 3 specific LSA – ❌ Correct Answer . These LSAs represent inter-area routes. Totally Stubby Areas do not allow Type 3 LSAs for specific routes , only for the default route (0.0.0.0/0).

B. Type 1 LSA – ✅ Allowed. These are Router LSAs generated by routers within the area and are necessary for OSPF to function.

C. Type 3 LSA that describes a default route – ✅ Allowed. This is the only Type 3 LSA permitted in a Totally Stubby Area. It provides a default route (0.0.0.0/0) to reach external destinations.

D. Type 2 LSA – ✅ Allowed if there are broadcast or NBMA networks in the area. These describe the network segment in multi-access environments and are generated by the DR.

Official Huawei Reference:

???? Huawei HCIP-Datacom-Core Technology Study Guide –

Chapter: OSPF Special Areas

" A totally stub area does not allow inter-area Type 3 LSAs or external Type 5 LSAs to enter. Only a default route is injected in the form of a Type 3 LSA (0.0.0.0/0), which greatly reduces the LSDB size. "

???? Also refer to:

Huawei VRP Command Guide > OSPF > Configuration Notes > OSPF Special Areas