H12-811_V1.0 Huawei HCIA-Datacom V1.0 Exam Free Practice Exam Questions (2025 Updated)

Detailed Explanation:The Time to Live (TTL) field in an IP packet is decremented by 1 each time the packet passes through a router. When the TTL reaches zero, the packet is discarded to prevent it from circulating indefinitely. (Reference: HCIA-Datacom Training Material, IP Packet Structure)

Comprehensive and Detailed Explanation:

A default route is used when no specific route matches a destination IP.

The correct syntax for a default static route is:

ip route-static 0.0.0.0 0.0.0.0

✅ Correct Option:

A. [Huawei] ip route-static 0.0.0.0 0.0.0.0 192.168.1.1

This correctly sets 192.168.1.1 as the next-hop for all unknown destinations.

❌ Incorrect Options:

B. 0.0.0.0 0.0.0.0 0.0.0.0 → Invalid because 0.0.0.0 cannot be a next-hop.

C. 0.0.0.0 255.255.255.255 192.168.1.1 → Invalid because the mask must be 0.0.0.0 for a default route.

D. [Huawei-Serial0] ip route-static 0.0.0.0 0.0.0.0 0.0.0.0 → Invalid interface syntax.

✅ Reference: HCIA-Datacom Routing Guide – Default Route Configuration

OSPF Packet Types:

LSA (Link State Advertisement): Contains topology information that routers use to build their LSDB.

LSU (Link State Update): Used to transmit multiple LSAs.

LSR (Link State Request): Requests specific LSAs from a neighbor router.

LSACK (Link State Acknowledgment): Confirms receipt of LSU packets​​.

Correct Packet for Acknowledgment:The LSACK packet is specifically designed to acknowledge LSU packets. Without acknowledgment, the LSU might be retransmitted unnecessarily.

Correct Answer:The OSPF packet used for acknowledgment is D (LSACK).

In STP, a port moves from Learning to Forwarding state after the Forward Delay timer has expired. This delay ensures stability by allowing time for the topology to converge before the port begins forwarding user traffic, thereby preventing loops in the network during the transition​.

In Huawei’s VRP system, the login timeout setting is applied specifically to Virtual Terminal (VTY) interfaces, which manage remote access connections such as Telnet or SSH. Configuring a login timeout on a VTY interface helps secure remote sessions by automatically disconnecting inactive users after a specified period​.

In a many-to-many non-NAPT (Network Address Port Translation) configuration, each private host requires a unique public IP address from the address pool. If only two public IP addresses are available and both are already in use by Host A and Host B, no IP will be available for Host C, preventing it from accessing the public network​.

In RSTP, both alternate and backup ports do not forward user traffic, but they can still receive and process BPDUs (Bridge Protocol Data Units). This allows the network to quickly reconfigure if the active path fails, as these ports are already participating in spanning tree calculations​.

Detailed Explanation:In Huawei VRP, the command-privilege command is used to modify the privilege level of a specific command. In this case, the command adjusts the privilege level of the save command within the user view to level 3, which is higher than the default level. This command does not modify the user's privilege level itself but changes the required privilege level to use the save command in the user view .

Comprehensive and Detailed Explanation:

In Spanning Tree Protocol (STP), the root bridge is selected based on:

Lowest priority (default = 32768, lower value preferred).

Lowest MAC address (if priorities are equal).

The given bridge priorities:

SWA: 4096 (Lowest priority → Automatically the root bridge).

SWB, SWC, SWD: 32768 (Default priority).

The stp root secondary command makes SWD the backup root (if SWA fails).

✅ Reference: HCIA-Datacom Switching Guide – STP Root Bridge Selection

To determine which switch will be selected as the root bridge after running the stp root secondary command on SWD, we need to analyze the Spanning Tree Protocol (STP) election process, as defined in IEEE 802.1D and aligned with HCIA Datacom documentation. Let’s break it down step by step:

Understanding STP and Root Bridge Election:

STP is used to prevent loops in Ethernet networks by electing a root bridge and creating a loop-free topology. The root bridge is the central point of the spanning tree, and all other switches calculate the shortest path to it based on path cost.

The root bridge is selected based on the Bridge ID (BID), which consists of two components:

Bridge Priority: A 16-bit value (default is 32768 for most switches, but it can be configured). Lower priority values are preferred.

MAC Address: If bridge priorities are equal, the switch with the lowest MAC address (the last part of the Bridge ID) becomes the root bridge.

The Bridge ID is typically written as Priority:MAC-Address. For example, a Bridge ID of 4096:0001-0203-04AA indicates a priority of 4096 and a MAC address of 0001-0203-04AA.

Analyzing the Given Bridge IDs:From the diagram, the Bridge IDs of the switches are:

SWA: Bridge ID = 4096:0001-0203-04AA (Priority = 4096, MAC = 0001-0203-04AA)

SWB: Bridge ID = 32768:0001-0203-04BB (Priority = 32768, MAC = 0001-0203-04BB)

SWC: Bridge ID = 32768:0001-0203-04CC (Priority = 32768, MAC = 0001-0203-04CC)

SWD: Bridge ID = 32768:0001-0203-04DD (Priority = 32768, MAC = 0001-0203-04DD)

Initially, the switch with the lowest Bridge ID (lowest priority, or lowest MAC if priorities are tied) is elected as the root bridge.

Comparing the priorities:

SWA has a priority of 4096, which is lower than the default priority of 32768 for SWB, SWC, and SWD.

Therefore, SWA is currently the root bridge because it has the lowest priority (4096) compared to the others (32768).

If priorities are equal, the MAC address is used as a tiebreaker, but here, SWA’s lower priority makes it the root bridge without needing to compare MAC addresses.

Effect of the stp root secondary Command on SWD:

The stp root secondary command (commonly used in Huawei switches, as per HCIA Datacom) is a configuration command that sets a switch as the secondary root bridge. This means the switch’s priority is automatically adjusted to a value lower than the default (32768) but higher than the primary root bridge’s priority, ensuring it becomes the root bridge if the primary root fails.

Specifically, in Huawei switches, running stp root secondary on SWD typically sets its priority to 28672 (which is lower than 32768 but higher than 4096, ensuring it does not override SWA unless SWA fails).

However, the question asks which switch will be selected as the root bridge after running this command on SWD, implying we need to determine the current root bridge and whether this command changes it immediately.

Importantly, the stp root secondary command does not immediately make SWD the root bridge if a switch with a lower priority (like SWA with 4096) already exists in the network. It only prepares SWD to become the root if the current root (SWA) fails or is removed.

Therefore, running stp root secondary on SWD adjusts its priority to 28672, but SWA remains the root bridge because its priority (4096) is still lower than SWD’s new priority (28672).

Determining the Root Bridge After the Command:

After running stp root secondary on SWD, its Bridge ID becomes 28672:0001-0203-04DD (Priority = 28672, MAC = 0001-0203-04DD).

We compare the Bridge IDs of all switches:

SWA: 4096:0001-0203-04AA (Priority = 4096)

SWB: 32768:0001-0203-04BB (Priority = 32768)

SWC: 32768:0001-0203-04CC (Priority = 32768)

SWD: 28672:0001-0203-04DD (Priority = 28672)

The switch with the lowest priority (and lowest MAC address if priorities are tied) is the root bridge.

SWA’s priority (4096) is the lowest, followed by SWD’s new priority (28672), and then SWB and SWC (32768).

Therefore, SWA remains the root bridge because its priority (4096) is lower than SWD’s new priority (28672) and all others.

Conclusion:

Initially, SWA is the root bridge due to its lowest priority (4096).

Running stp root secondary on SWD changes its priority to 28672, making it the secondary root (backup root) if SWA fails, but it does not immediately make SWD the root bridge.

Thus, SWA continues to be the root bridge after the command is run on SWD.

Answer: B (SWA)

References from HCIA Datacom Documents:

HCIA Datacom V3.0, Chapter 6: Spanning Tree Protocol – Root Bridge Election and Configuration Commands

Huawei STP Configuration Guide (HCIA Datacom Certification Material) – stp root primary and stp root secondary Commands

IEEE 802.1D Standard – Bridge ID and Root Bridge Selection Process

Detailed Explanation:

• Option A: Incorrect. UDP (User Datagram Protocol) does not use SYN or ACK flags, as it is a connectionless protocol and does not establish a connection before data transfer. SYN and ACK flags are features of TCP (Transmission Control Protocol), which establishes connections using a three-way handshake. (Reference: HCIA-Datacom Training Material, Transport Layer Protocols)

• Option B: Incorrect. UDP is suitable for delay-sensitive traffic (such as video or voice) because of its low overhead. However, UDP does not have a sequence number field or support reassembly, as it does not guarantee packet order or reliability. (Reference: HCIA-Datacom Training Material, UDP Characteristics)

• Option C: Correct. TCP requires a three-way handshake to establish a connection and a four-way handshake to terminate it, involving SYN, ACK, FIN flags for reliability. (Reference: HCIA-Datacom Training Material, TCP Connection Establishment and Termination)

• Option D: Correct. The well-known port number range is defined as 0 to 1023, and these are reserved for widely used protocols such as HTTP, FTP, and DNS. (Reference: HCIA-Datacom Training Material, Port Numbering)

In VRP, the "-a" parameter in the ping command allows specifying a source IP address for the echo request. This can be helpful in testing connectivity from a specific interface on the device, which is useful in verifying path accessibility or troubleshooting issues with certain network segments​.

Detailed Explanation:Making a call on a landline telephone involves network communication. Though it uses a traditional telephone network (Public Switched Telephone Network, PSTN), the process of sending and receiving voice data through a wired system qualifies as network communication. The voice signals are converted into electrical signals, transmitted over the network, and then converted back into voice signals on the receiving end .

Detailed Explanation:Local Area Networks (LANs) cover a small geographic area, such as a home or office. They typically connect computers and devices within a limited area, such as a single building. In this case, both a home network and an office network of a company qualify as LANs. On the other hand, a Metropolitan Area Network (MAN) covers a city-wide area, and the Internet is a global network, so these are not LANs .

IP Address Uniqueness on VLANIF Interfaces:Each VLANIF interface represents a different logical interface, often tied to distinct subnets. IP addresses for VLANIF interfaces must be unique on the same switch to prevent address conflicts and routing issues​​.

Correct Answer:TRUE. The IP addresses of VLANIF interfaces on the same switch must be different.

Step 1: Understanding MAC Address Table Lookup

When Host A sends a frame with MAC-B as the destination, SWA checks its MAC address table to determine the correct port to forward the frame.

According to the MAC table, MAC-B is associated with interface G0/0/2.

Step 2: Forwarding Behavior

Since SWA knows the destination MAC address and its associated interface, it will forward the frame only through G0/0/2.

Step 3: Analyzing the Answer Choices

Option A (Correct - Forwards only through G0/0/2): ✅

SWA correctly forwards the frame to G0/0/2, where HostB is connected.

Option B (Incorrect - Forwards through G0/0/3): ❌

MAC-B is not associated with G0/0/3, so the switch will not forward the frame there.

Option C (Incorrect - Floods the frame): ❌

Flooding occurs only when the MAC address is unknown, but in this case, MAC-B is known.

Option D (Incorrect - Discards the frame): ❌

The switch only discards frames if there’s a security violation or filtering rule, which is not mentioned here.