H12-811_V1.0 HCIA-Datacom V1.0 Exam Questions and Answers

In RSTP (Rapid Spanning Tree Protocol), the Backup port serves as a backup for the Designated port on the same bridge segment, not the root port. If the root port fails, the alternate port, not the backup port, takes over to maintain connectivity to the root bridge. The backup port does not have the capability to replace the root port​.

Detailed Explanation:The Type/Length field value of 0x0800 indicates that the upper-layer protocol is IPv4. However, the length of the IPv4 header can range from 20 to 60 bytes, not the length of the entire upper-layer packet. The field refers to the type of the encapsulated protocol, and the length is not constrained to the header alone​​.

Detailed Explanation:When a command entered on Huawei’s Versatile Routing Platform (VRP) is incomplete, VRP generates an error message indicating that the command is incomplete at a specific position (designated by 'A'). This message helps administrators identify where additional parameters are needed to complete the command syntax. Other error messages indicate issues such as excess parameters or ambiguous commands. (Reference: HCIA-Datacom Lab Guide, VRP Command Syntax)

Disabling STP on a network with redundant paths between switches leads to a Layer 2 loop, which can cause broadcast storms and network congestion. STP is essential for preventing such loops by blocking redundant paths until needed for redundancy, ensuring network stability​.

The telnetlib module in Python provides functions to interact with Telnet servers, allowing Python scripts to automate Telnet sessions. This module is widely used in network automation and scripting tasks, where Telnet is used to access and manage network devices remotely​.

Impact of Loops in Layer 2 Networks:Loops in a Layer 2 network cause packets to be repeatedly forwarded, leading to broadcast storms, high CPU utilization, and network disruption​​.

Correct Answer:TRUE. Loops can cause broadcast storms on Layer 2 networks.

Detailed Explanation:The ACL (Access Control List) configuration only permits IP address 172.16.105.2. By applying this ACL to the Telnet server, only devices from this IP can establish a Telnet connection, while all others are denied access. (Reference: HCIA-Datacom Training Material, ACLs and Telnet Access Control)

Detailed Explanation:The 802.11ax standard, also known as Wi-Fi 6, supports theoretical speeds over 5 Gbit/s and is designed for high-efficiency wireless networking in dense environments. (Reference: HCIA-WLAN Training Material, IEEE 802.11 Standards)

Comprehensive Explanation: The country code setting on wireless devices like access points determines the allowable transmission frequencies and maximum transmission power based on the regulatory requirements of the specific region. For example, certain frequency channels or power levels may be restricted in different countries to avoid interference with other services, and the country code configuration ensures that the device operates within those legal limits.

Detailed Explanation:

The subnet 200.200.200.200/30 allows two usable IP addresses, 200.200.200.201 and 200.200.200.202. These two addresses can communicate with each other directly, without the need for routing .

Comprehensive Explanation: When Router A forwards the packet to Router B, the destination IP address (11.0.12.1) remains unchanged as it is still meant for Host B. However, the destination MAC address changes to MAC-B, which belongs to Host B, since MAC addresses are only used for local network hops​

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​.

DHCP (Dynamic Host Configuration Protocol) can allocate various network parameters, including:

IP address: Assigns a unique IP to each client.

Gateway address: Provides the default gateway for routing traffic.

DNS server address: Allows domain name resolution. The DHCP server does not assign an operating system, as this is outside its scope​.

The default route preference on Huawei VRP places Direct routes at the highest priority, followed by Static routes, then RIP, and finally OSPF. Direct routes are most trusted as they represent directly connected networks, while OSPF, being a dynamic protocol with more administrative distance, is prioritized lower by default​.

SNMP Agent Functionality:Each network device running SNMP includes an agent process that collects and manages information about the device's operations. This process interfaces with the SNMP manager to provide network monitoring and management capabilities​​.

Comprehensive Explanation: In Software-Defined Networking (SDN), the control plane (which makes decisions about where to send traffic) is separated from the forwarding plane (which actually moves packets to their destinations). This separation allows for centralized control and management of the network, enabling programmability and greater flexibility. SDN controllers manage the control plane, while individual switches or routers handle the forwarding of data.

Comprehensive Explanation: The wildcard mask 0.0.254.255 corresponds to a range of IP addresses where the second octet can vary between 2 and 4, and the third octet can vary between 0 and 255. This means the ACL rule matches IP addresses in the range 10.0.2.0 to 10.0.4.255. The only option that falls within this range is 10.0.4.5, making it the correct answer.

In OSPF, routers first synchronize their LSDBs (Link-State Databases) through an exchange of LSAs (Link State Advertisements) before reaching the Full state. Only after full synchronization of the LSDB does the OSPF neighbor state move to Full. This ensures both routers have consistent routing information before establishing full adjacency​.

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)

In OSPF networks, a DR (Designated Router) is elected for each broadcast domain, such as each Ethernet segment. Given the topology where there are multiple Ethernet segments, a DR will be elected in each segment, resulting in three DRs based on the configuration and network design​.

Detailed Explanation:The Priority Code Point (PCP) field in an 802.1Q VLAN tag is 3 bits long, which gives it a value range of 0 to 7. This field is used to indicate the priority of the frame, with higher values indicating higher priority​​.

In Huawei devices, advanced ACLs use a number range from 3000 to 3999. These ACLs allow more granular control over traffic by permitting conditions based on source and destination IP addresses, protocol types, and ports, making them suitable for complex filtering requirements​.

Detailed Explanation:Small campus networks are characterized by simple architecture, limited user counts, and straightforward network requirements. Wide coverage is typically associated with larger campus or enterprise networks. (Reference: HCIA-Datacom Training Material, Campus Network Characteristics)

SNMP Message Types:

get-request: Sent by the NMS to retrieve data from a device.

set-request: Used by the NMS to modify device settings.

get-response: Sent by the device in response to a get-request.

trap: Sent automatically by a device to notify the NMS of an event.

Why "trap" Is Correct:

If a registered event occurs (e.g., interface down, high CPU usage), the device proactively sends a trap to alert the NMS.

Conclusion:

Since traps notify abnormal events, the correct answer is A (trap).

References: HCIA-Datacom V1.0 Certification Guide, Chapter 7: SNMP and Network Monitoring.

Detailed Explanation:Static MAC address entries are manually configured and stored in the switch's configuration file, making them persistent across reboots. These entries remain in the MAC address table after a restart, unlike dynamic entries, which are lost. (Reference: HCIA-Datacom Training Material, MAC Address Table Types)

Comprehensive Explanation: The output shows that the current and next startup configurations are different. Specifically, the startup saved-configuration file is flash:/vrpcfg.zip, and the next startup saved-configuration file is flash:/backup.zip, indicating that changes have been made and the system will use a different configuration file at the next reboot​

Comprehensive Explanation: In this configuration, LSW1 and LSW2 have trunk links that allow VLAN 10 to pass between them. When a ping is sent from R1, the frame is tagged with VLAN 10 on LSW2, and this tagged frame is forwarded to LSW1. Since the trunk allows VLAN 10, the tagged data frame is successfully received and processed by LSW1.

MAC Address Analysis:

MAC addresses starting with 01-00-5E are reserved for IPv4 multicast by the IANA.

Why Other Options Are Incorrect:

A: The address is valid and reserved for multicast.

C: Broadcast addresses use FF-FF-FF-FF-FF-FF.

D: Unicast addresses are typically hardware-assigned and do not use this prefix.

References: HCIA-Datacom V1.0 Certification Guide, Chapter 7: Ethernet Basics.

Detailed Explanation:If the username does not contain the delimiter "@" followed by a domain name, the user is automatically assigned to the default domain. In this case, since the username "huawei" does not specify a domain, the user belongs to the default domain​​.

The default port number for Telnet is 23. This standard port assignment allows Telnet clients to connect to Telnet servers, facilitating remote management and troubleshooting tasks on network devices. Ports are preassigned to services to streamline network communication and reduce conflicts​.

Detailed Explanation:APs can be added to an AC using multiple methods. You can add them when they are online, offline, or allow the AC to automatically discover them. Additionally, unauthorized APs can be manually confirmed for security​.

Comprehensive Explanation: When a switch port receives an untagged frame, the port adds the default VLAN ID, known as the PVID (Port VLAN ID), to the frame. This ensures that the frame is associated with a specific VLAN before it is forwarded. The PVID represents the VLAN to which the port belongs and is used when the port receives untagged traffic. This behavior is typical for access and hybrid ports in a VLAN-enabled switch configuration.

Analysis of Possible Causes:

Option A: "The administrator account has been disabled" is a possible cause as a disabled account cannot access the system even if Telnet is enabled.

Option B: Incorrect because the Telnet service being disabled would affect all users, not just one administrator.

Option C: "The administrator account has been deleted" is a valid reason as a deleted account cannot log in.

Option D: "The user level of the administrator account has been changed to 0" is correct. User level 0 typically has insufficient privileges for Telnet access​​.

Routing Table and Equal-Cost Routes:When multiple routes to the same destination network have the same cost (e.g., metric or administrative distance), they are referred to as "equal-cost routes." Routers use load balancing to distribute traffic across these routes​​.

Analysis of Options:

Option A: "Sub-optimal routes" are routes that are not preferred due to higher cost or less desirable metrics.

Option B: "Multipath routes" is a general term but does not specify equal cost, making it less precise.

Option C: "Equal-cost routes" is correct as the scenario specifies the same destination network with the same cost.

Option D: "Default routes" are used when no specific route matches the destination, which is unrelated to the given scenario​.

Correct Answer:The routes are C (Equal-cost routes).

IPv6 Address Types:

Unicast: Identifies a single interface.

Anycast: Identifies a set of interfaces, delivering to the nearest one.

Multicast: Delivers to multiple interfaces.

Broadcast: Does not exist in IPv6; replaced by multicast addressing​​.

Comprehensive Explanation: The quit command is used to return from the system view to the user view in Huawei's VRP (Versatile Routing Platform). This command allows users to exit the current configuration mode and revert to the default user view. For example, when you are in the system view and you want to return to the user view, typing quit takes you back to the initial prompt without saving the current configuration​​.

Encapsulation is the process of adding headers and trailers to data at each layer of the OSI model as the data moves from the application layer to the physical layer. Decapsulation is the reverse process when data is received. These processes are critical in implementing network communication, ensuring the proper function of protocols, and assisting in locating faults during data transmission. They do not, however, shorten packet length​

A broadcast address, with all host bits set to 1, is used for broadcasting messages to all devices within a network segment. It cannot be assigned to a specific host, as its purpose is to reach every device in the subnet. Therefore, it is reserved for broadcast communication and cannot serve as an individual host address​.

Comprehensive Explanation: In RSTP (Rapid Spanning Tree Protocol), G0/0/3 of SWB is an Alternate Port because it provides a redundant path to the root bridge, while G0/0/3 of SWA is a Designated Port, forwarding traffic away from the root bridge. Similarly, G0/0/2 of SWA is also a Designated Port because it forwards traffic to other segments of the network. Alternate Ports are used to provide backup paths, while Designated Ports are the forwarding ports on a given segment.

Detailed Explanation:To manage a router in a remote branch office, Telnet is a suitable option as it allows remote access over a network. Unlike a console connection, which requires physical access, Telnet enables remote management as long as the administrator has network connectivity to the router. FTP is used for file transfer, and DHCP is used for dynamic IP address allocation, not for management​​.

In STP, the root bridge is elected based on the lowest bridge priority. If there is a tie in bridge priority, the device with the lowest MAC address is selected as the root bridge. This process ensures a stable, predictable root bridge selection in the network​.

Main Functions of Routers:Routers primarily operate at the Network Layer (Layer 3) of the OSI model, forwarding data packets based on destination IP addresses and maintaining routing tables for decision-making.

Analysis of Options:

Option A: "Routers forward data packets based on source IP addresses" is incorrect, as routers use the destination IP address in a packet to determine its forwarding path, not the source IP address​​.

Option B: "Routers enable devices on the same network segment to communicate with each other" is not a function of routers. Devices on the same segment communicate using switches or hubs, which operate at the Data Link Layer (Layer 2)​​.

Option C: "Routers forward data packets according to routing tables" is a correct function, as routers rely on routing tables to determine the best path for forwarding packets.

Option D: "Routers learn routes through multiple routing protocols and add them to the routing table" is a correct function of routers in dynamic routing scenarios​.

Correct Answer:The functions A and B are not main functions of routers.

Detailed Explanation:SNMP-enabled devices can send traps, which are unsolicited messages that notify network administrators of significant events or issues, helping them to detect and resolve problems quickly​.

SNMP (Simple Network Management Protocol) supports the use of traps, which are unsolicited messages sent to the SNMP manager when specific events occur. Traps enable devices to report faults or important events as they happen, facilitating proactive fault management and quicker response times by network administrators​.

Eth-Trunk Functionality:An Eth-Trunk interface can operate as both a Layer 2 and Layer 3 interface depending on the configuration. For example:

As a Layer 2 interface, it can aggregate Ethernet links for switching.

As a Layer 3 interface, it can aggregate links for routing​.

Correct Answer:FALSE. Eth-Trunk interfaces can function as both Layer 2 and Layer 3 interfaces.

Router A would have three TCP connections in this scenario:

One for the Telnet session from host A to router A.

One for the FTP control connection to router B.

One for the FTP data connection to transfer the configuration file. These TCP connections facilitate the remote login and file transfer across the network​.

Detailed Explanation:While a switch will typically forward a unicast frame based on its MAC address table, certain scenarios like port security or VLAN restrictions may prevent the frame from being forwarded even if a MAC entry exists. (Reference: HCIA-Datacom Training Material, MAC Address Table and Frame Forwarding)

The BSSID (Basic Service Set Identifier) serves as the MAC address identifier for each Virtual Access Point (VAP) on an AP. Each BSSID uniquely identifies an SSID on a specific radio of an AP, allowing clients to associate with the correct access point in a multi-AP environment​.

The country-code command is used on an AC (Access Controller) to specify the country code, which aligns the wireless settings with local regulatory standards. Setting the correct country code ensures compliance with regional RF (Radio Frequency) regulations, such as frequency bands and transmission power limits​.

SNMP Port Numbers:

161: Used for SNMP managers to send requests to agents.

162: Used by SNMP agents to send trap or alarm messages to the Network Management System (NMS).

163 and 164: Not commonly used in SNMP operations.

Given correct configuration, hosts within the same subnet should be able to communicate, so the host at 10.0.12.1 can ping the host at 10.0.12.2. This scenario assumes correct interconnectivity and absence of firewall or ACL rules that would block the communication​.

Command Output Overview:

The command display startup is used to check the configuration of the startup system software, configuration files, license files, and other related settings on Huawei routers. The output in this case provides details about:

The current system software (ar2220-v200r003c00spc200.cc).

The next startup system software (ar222b-v200r003c00spc200.cc).

Backup and saved configuration files, which are not defined (null).

Analysis of Options:

Option A: "The system file for next startup cannot be modified."This statement is false because the system file for the next startup can be modified using the startup system-software command. The file path for the next startup system software (ar222b-v200r003c00spc200.cc) indicates that it has been configured and can be changed by the administrator. The command syntax is supported as per Huawei's documentation​​.

Option B: "The startup system software <startup-software-name> command can be used to modify the system software for next startup."This is true and matches the functionality provided by Huawei's routers. The command allows administrators to specify the software package to be used at the next system reboot​​.

Option C: "The running configuration file is not saved."This is true as the Startup saved-configuration file is listed as null, meaning that no configuration file has been saved for startup. Saving the running configuration is necessary to ensure settings persist after a reboot​​.

Option D: "The system file used for the current startup is ar2220-v200r003c00spc200.cc."This is true as per the output under Startup system software, which confirms the system file used in the current boot process​​.

Correct Statement Selection:Based on the analysis, the statement "The system file for next startup cannot be modified" is false. This matches the system's behavior, where administrators are allowed to modify the next startup file using relevant commands.

References:

Huawei HCIA-Datacom V1.0 Training Material and Lab Guide​​.

Command-line operations from Huawei routers, as documented in the training materials and lab environments​​.

Command Overview:The Huawei Versatile Routing Platform (VRP) uses specific commands to manage file systems and view directory contents. While the dir command is used to list files in the current directory, the pwd command is not supported in VRP environments. Instead, the current working directory is displayed as part of the command prompt in VRP​​​.

Command Analysis:

dir Command:This command is supported and displays the list of files and subdirectories in the current directory. Example:

dir

Output includes filenames, sizes, and other metadata.

pwd Command:The pwd command is commonly used in UNIX/Linux systems to print the current working directory. However, this command is not available on VRP. VRP automatically shows the current directory in its prompt, making pwd unnecessary.

Correct Answer:Since only dir is valid, the statement is false. The correct answer is B (FALSE).

Detailed Explanation:Each Virtual Access Point (VAP) on an AP is identified by a unique Basic Service Set Identifier (BSSID), which is the MAC address used at the data link layer. The SSID is a human-readable network name, while the BSSID is the technical identifier​.

Detailed Explanation:With a /30 subnet mask, the valid IP range is 192.168.1.0 - 192.168.1.3:

192.168.1.3 is the broadcast address, so it can be a destination.

192.168.1.1 and 192.168.1.2 are host addresses.

255.255.255.255 is the limited broadcast address, which any device can use to reach all hosts on the local network.

(Reference: HCIA-Datacom Training Material, IP Addressing and Subnetting)

The command lease day 0 hour 10 sets the lease time for DHCP-assigned IP addresses to 10 hours. This setting provides a short, specific lease duration for dynamically assigned IP addresses, which can be useful in networks where devices frequently join and leave, minimizing IP address retention time​.

Detailed Explanation:

In RSTP (Rapid Spanning Tree Protocol), if an edge port receives a BPDU (Bridge Protocol Data Unit), it loses its edge status and becomes a regular STP port. This ensures that the edge port behaves as expected when connecting to another switch.

In trunk mode, the interface can forward frames tagged with VLANs specified in the allow-pass list (here, VLAN 100) without removing tags. However, if an untagged frame is received, it is assigned to the PVID (here, VLAN 200). This configuration allows both tagged and untagged traffic, with the PVID determining the VLAN for untagged frames​.

Comprehensive Explanation: SNMP (Simple Network Management Protocol) consists of several key components:

Management Information Base (MIB): A database containing the network management data.

Managed object: The individual objects (such as interfaces or devices) that SNMP manages.

Agent process: The software running on the managed device that reports data to the NMS.

NMS (Network Management System): The centralized system that collects data from managed devices using SNMP.

All these components work together to monitor, configure, and manage network devices.

Detailed Explanation:Static routing does not automatically recover from link failures; manual reconfiguration is required if a static route path becomes invalid. Dynamic routing protocols, on the other hand, adapt automatically to network changes, adjusting routes as needed. (Reference: HCIA-Datacom Training Material, Static vs. Dynamic Routing)

Comprehensive Explanation: A routing table contains several key elements:

Cost: Also known as metric, this indicates the cost associated with reaching a specific destination, such as the number of hops or link speed.

Next-hop address: This is the IP address of the next device along the route that packets should be forwarded to.

Protocol: The routing protocol (e.g., OSPF, RIP) that determined the route.

Interface: The physical or logical interface through which the router sends packets to reach the destination.

Destination/Mask: The destination network or subnet and the associated subnet mask define the range of IP addresses for which this route is valid. These elements together allow routers to efficiently forward traffic to the correct destinations.

Understanding ARP Entries:

Each ARP entry associates a MAC address with an IP address dynamically or statically.

In the table, the MAC address 00e0-fc99-9999 is linked to multiple IP addresses across different interfaces.

Dynamic MAC Address Assignment:

As the host changes its IP address, the MAC address remains consistent.

Conclusion:

The statement is TRUE because the MAC address 00e0-fc99-9999 appears with three different IP addresses dynamically.

References: HCIA-Datacom V1.0 Certification Guide, Chapter 5: ARP Protocol.

Comprehensive Explanation: An ACL (Access Control List) is used to define rules for permitting or denying packets based on criteria such as IP addresses, protocols, or ports. However, the ACL only takes effect when it is applied to a service module, such as an interface or a firewall rule. This ensures that traffic is filtered according to the ACL rules as it passes through the device. Without being applied, the ACL rules are inactive and do not influence traffic.

Comprehensive Explanation: The interface configuration shows that VLANs 2, 3, and 100 are tagged, meaning frames belonging to these VLANs are transmitted with VLAN tags. VLANs 4 and 6 are untagged, meaning frames for these VLANs are transmitted without tags. The command port hybrid tagged vlan 2 to 3 100 specifies that data frames for VLANs 2, 3, and 100 are transmitted with tags, while port hybrid untagged vlan 4 6 configures the interface to transmit untagged frames for VLANs 4 and 6.

Detailed Explanation:

Dynamic routing protocols, such as OSPF and RIP, automatically discover and generate routes, adjusting when network topology changes occur. This helps in reducing the manual configuration required by static routes and ensures that the network adapts efficiently to changes such as link failures or the addition of new routes.

Router Functionality:Routers operate at the Network Layer (Layer 3) of the OSI model. They use IP addresses to forward packets between different networks and determine the best path for data transmission based on routing tables​​.

Analysis of Options:

Option A: "Network layer" is correct, as routers are Layer 3 devices.

Option B: "Transport layer" handles end-to-end communication and reliability (e.g., TCP/UDP), not routing.

Option C: "Data link layer" is for local node-to-node data transfer (e.g., MAC addresses), handled by switches.

Option D: "Application layer" is for user-facing software interactions (e.g., HTTP, FTP).

Correct Answer:Routers work at the A (Network layer).

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.