H12-811_V2.0 HCIA-Datacom V2.0 Questions and Answers

A router works mainly at the network layer . When it receives a frame, it removes the Layer 2 header and trailer, examines the destination IP address in the Layer 3 header, consults the routing table, selects the outgoing interface, and then re-encapsulates the packet into a new Layer 2 frame for the next hop. Therefore, statement B is true and is not part of the answer.

Statement A is false because the router does not create a new destination IP address during normal forwarding. The source and destination IP addresses remain unchanged end to end unless special functions such as NAT are used. Statement C is false because routing-table lookup is based on the destination IP address, not on TCP or UDP port numbers. Statement D is also false because normal IP routing does not inspect application-layer content to determine the outgoing interface. That decision is made from the network-layer destination address and the routing table. This question tests the layered forwarding logic of routers in TCP/IP networks.

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To check OSPF-learned routes in the global IP routing table , the correct command is display ip routing-table protocol ospf , so option A is correct. This command filters the routing table and shows only the routes whose source protocol is OSPF. It is especially useful when verifying whether OSPF-learned routes have been successfully installed into the forwarding table after neighbor establishment and LSDB calculation.

Option B , display ospf peer, is used to check OSPF neighbor information and adjacency states, not the routing table. Option C , display ospf interface, shows OSPF-related parameters on interfaces such as timers, network type, and cost. Option D , display ospf routing, displays OSPF route information maintained by the OSPF process itself, but the question specifically asks about routes in the global routing table , which is the RIB used for actual forwarding decisions. HCIA-Datacom distinguishes between protocol-specific route information and the final routing table seen by the device. Understanding this distinction helps engineers verify whether a protocol has only learned topology information or has actually produced usable forwarding entries.

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An Ethernet switch learns MAC address entries dynamically by examining the source MAC address of incoming frames. When SW1 first receives frames from PC1 on GE1/0/1, it creates a MAC address table entry mapping PC1’s MAC address to that port. If PC1 later sends frames that arrive on GE1/0/2, SW1 updates the learned entry to reflect the new incoming interface. Therefore, option B is correct: SW1 saves the mapping between PC1’s MAC address and GE1/0/2 and removes or overwrites the old mapping associated with GE1/0/1.

Option A is incorrect because a single dynamic MAC address is not normally maintained on two different ports within the same VLAN at the same time; that would cause forwarding ambiguity. Option C is incorrect because a normal move of one MAC address does not require clearing the entire MAC table. Option D is also incorrect because switches update MAC learning dynamically upon receiving new source traffic and do not have to wait for the previous entry to age out. HCIA-Datacom uses this principle to explain MAC address learning, migration, and troubleshooting of loops or host movement in switched Ethernet networks.

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This statement is true . From the routing table, the entry 10.0.12.0/24 Direct ... NextHop 10.0.12.1 Interface Vlanif2 indicates that the network 10.0.12.0/24 is directly connected through Vlanif2 , and the local interface address associated with that directly connected network is 10.0.12.1 .

This conclusion is further supported by the host route 10.0.12.1/32 Direct ... 127.0.0.1 Vlanif2, which represents the local IP address of the interface itself. On Huawei devices, when an IP address is configured on an interface, the routing table commonly generates a direct route to the connected network, a host route to the interface IP itself, and sometimes a host route to the broadcast address where applicable in IPv4. Therefore, from the displayed entries, it can indeed be inferred that VLANIF 2 has the IP address 10.0.12.1/24 . HCIA-Datacom uses these routing-table characteristics to help learners identify connected interfaces, local addresses, and route origins during troubleshooting and route analysis on routers and Layer 3 switches.

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The address 224.0.0.1/24 cannot be configured as a normal host IP address by default because it belongs to the Class D multicast address range . IPv4 multicast addresses range from 224.0.0.0 to 239.255.255.255 and are reserved for multicast group communication rather than assignment to host interfaces as ordinary unicast addresses. Therefore, option D is correct.

The other three options are all private unicast address ranges and can be configured on hosts in private networks. 10.0.0.1/8 belongs to the 10.0.0.0/8 private range, 172.16.1.1/16 belongs to the 172.16.0.0/12 private range, and 192.168.1.1/24 belongs to the 192.168.0.0/16 private range. These are commonly used in enterprise and campus networks. HCIA-Datacom teaches that host IP address planning must distinguish between unicast, multicast, loopback, broadcast, and other special-purpose ranges. Multicast addresses identify multicast groups and are processed differently by hosts and network devices, so they are not valid default host addresses for ordinary end-to-end IP communication.

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This statement is true . When a device has multiple routes to the same destination prefix, route selection is based first on the longest prefix match , and when prefix length is the same, the device compares the route preference or administrative priority associated with each routing source. On Huawei devices, a direct route has a better preference than a static route , so the direct route is selected first when both routes have the same destination and mask.

A direct route is generated automatically when an IP address is configured on an interface and that interface is Up. Because the destination network is directly connected, this route is considered more trustworthy and efficient than a manually configured static route pointing to the same prefix. HCIA-Datacom uses this principle to explain route selection, routing-table generation, and troubleshooting cases where a configured static route does not appear as the active route because a direct or dynamic route has higher priority. This is a basic but important concept in IP forwarding and helps engineers correctly interpret routing tables on Huawei routers and Layer 3 switches.

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In STP, the root bridge has all its active ports elected as designated ports on each connected segment. On non-root switches, one port is selected as the root port , and on each LAN segment, one designated port is elected based on the best BPDU. Since SW1 is the root bridge and all links have equal cost, the election depends first on the path cost to the root, then on bridge ID, and then on port ID if needed.

According to the topology, the ports that become designated are GE1/0/2 of SW2 , GE1/0/1 of SW2 , and GE1/0/3 of SW3 , which correspond to option A , B , and C . Option D is not a designated port in this topology because that segment has another port with a superior BPDU and therefore SW4’s port does not win the designated-port election. HCIA-Datacom emphasizes that designated ports are elected per segment , not per switch, and that every non-root switch must compare received BPDUs to determine root and designated roles. This question tests the ability to apply STP election logic rather than simply memorizing port-role definitions.

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This statement is false . On Huawei devices, the domain to which a user belongs is usually determined by the domain part carried in the user name, for example user@huawei.com. However, if the specified domain is not configured on the NAS device, authentication does not necessarily fail immediately . In many cases, the device can use a default domain for authentication processing, depending on the AAA configuration.

Huawei AAA supports both an administrator user default domain and a normal user default domain . If a user name does not match a configured domain, or the domain carried in the user name is unavailable, the device may fall back to the default domain and continue authentication according to the configured policy. Therefore, the statement is incorrect because it treats authentication failure as unavoidable in every such case. HCIA-Datacom emphasizes domain-based AAA processing because it allows different groups of users to use different authentication, authorization, and accounting methods. At the same time, learners must understand the function of default domains, which provide flexibility in real deployments and prevent unnecessary authentication failures in some login scenarios.

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This statement is false . In campus network VLAN planning, VLAN IDs do not have to be allocated strictly consecutively without any gaps. In fact, leaving some reserved VLAN IDs is often a practical and recommended design approach. VLAN planning should focus on clarity, scalability, maintainability, and service separation , rather than on forcing all VLAN IDs to be contiguous.

For example, an administrator may reserve certain VLAN ranges for user access, voice services, management, wireless services, guest access, future expansion, or specific departments. Such structured planning makes later network expansion easier and reduces the risk of service conflicts or disruptive renumbering. HCIA-Datacom emphasizes that good campus network planning should consider current requirements and future growth. Consecutive allocation may look tidy at first, but it can actually reduce flexibility and make later additions more difficult. Therefore, the idea that VLAN IDs must be assigned consecutively without redundancy to avoid omissions is not a correct design principle. Reasonable reservation and categorized allocation are often more beneficial in real enterprise campus networks.

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Duplicate Address Detection ( DAD ) is an IPv6 mechanism used to verify that a unicast address is not already in use before the address is assigned to an interface. DAD is implemented using Neighbor Solicitation (NS) and Neighbor Advertisement (NA) messages, which are part of the ICMPv6 Neighbor Discovery protocol. Therefore, options A and D are correct.

When a host wants to verify a tentative IPv6 address, it sends an NS message for that address. If another node on the link is already using that address, that node responds with an NA message, indicating the address is duplicated and cannot be assigned. If no NA is received within the required period, the host assumes the address is unique and can use it. Options B and C are incorrect because Router Solicitation (RS) and Router Advertisement (RA) are used for router discovery, prefix advertisement, and stateless address autoconfiguration, not for DAD itself. HCIA-Datacom emphasizes the distinction between Neighbor Discovery functions, including address resolution, next-hop reachability, router discovery, and duplicate address detection in IPv6 networks.

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This statement is true . ARP is a Layer 2 broadcast-based protocol used to resolve an IPv4 address into a MAC address within the same broadcast domain. If two PCs are connected to the same switch but cannot learn each other’s ARP entries, one likely reason is an incorrect VLAN configuration .

For example, if PC1 and PC2 are placed in different VLANs, or if one interface is configured with the wrong access VLAN, ARP broadcast frames from one PC will not reach the other PC because VLANs separate Layer 2 broadcast domains. As a result, the ARP request will not be received by the peer, and the MAC address cannot be resolved. Other causes may also exist, such as incorrect IP addressing, port isolation, or security policies, but VLAN misconfiguration is a very common and valid cause in campus switching scenarios. HCIA-Datacom teaches that ARP communication depends on correct Layer 2 domain membership, and VLAN planning or interface configuration errors often directly affect host-to-host communication even when both hosts are physically connected to the same switch.

This statement is false . In Layer 3 in-path WLAN networking , the WAC and Fit APs communicate over Layer 3, which means the APs must discover the WAC through methods that are valid across Layer 3 boundaries. Broadcast is a Layer 2 mechanism and cannot normally be used for WAC discovery across Layer 3 networks. Therefore, saying that APs can obtain the WAC address through broadcast or DHCP in this scenario is incorrect.

In Huawei WLAN deployments, Fit APs can commonly discover the WAC address through methods such as DHCP option-based discovery , DNS , or preconfigured controller information, depending on the deployment model and product features. Because the WAC and AP are not in the same Layer 2 broadcast domain in Layer 3 in-path networking, broadcast discovery is not the standard mechanism here. HCIA-Datacom stresses the difference between Layer 2 direct discovery and Layer 3 discovery methods because this affects initial AP registration, CAPWAP establishment, and troubleshooting when APs fail to go online. Understanding the discovery mechanism is essential when planning IP addressing, DHCP options, and controller placement in enterprise WLAN designs.

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In the standard TCP/IP forwarding model, transport-layer headers such as TCP and UDP headers are added by the source host and are mainly interpreted by the destination host. Routers that forward packets between the source and destination operate primarily at the network layer , using the destination IP address in the IP header to make forwarding decisions. Therefore, under normal routing behavior, routers do not process transport-layer header information when deciding how to forward packets.

This is a key concept in layered communication. The source host encapsulates application data with a transport-layer header, then with an IP header, and finally with a data-link header. Each router along the path removes only the Layer 2 frame header, checks the Layer 3 destination IP information, decrements TTL, recalculates the IP header checksum when required, and forwards the packet. The transport-layer content remains unchanged in normal forwarding. HCIA-Datacom uses this principle to explain end-to-end communication and layer responsibilities. Although advanced devices may inspect higher-layer information for security or policy purposes, standard router forwarding in the basic TCP/IP model does not depend on transport-layer processing.

This statement is false because although Area 0 is indeed the backbone area , the statement about the area ID range is incorrect. In OSPF, the area ID is a 32-bit value , which can be represented either in decimal format or in IPv4 address format such as 0.0.0.0. It is not limited to the numeric range 0 to 255 .

For example, an area can be configured as 0, 1, 100, or in dotted-decimal form such as 0.0.0.1 or 0.0.0.10, depending on implementation and configuration style. HCIA-Datacom teaches that OSPF uses hierarchical area design to improve scalability, reduce SPF calculation scope, and optimize LSA flooding. The backbone area , which is Area 0, serves as the transit area connecting all non-backbone areas in a standard OSPF design. Therefore, the second part of the statement is correct, but the first part is wrong, making the entire statement false. This question tests whether the learner understands both the function of Area 0 and the actual format of OSPF area identifiers.

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Option D is correct. The AAA configuration binds the domain huawei.com to the authentication scheme auth1 , which uses RADIUS as the authentication mode, and to the accounting scheme acc1 , which also uses RADIUS. Therefore, when a user logs in with a user name in the format hcia-datacom@huawei.com , the device parses the suffix @huawei.com, matches the domain, and applies the configured RADIUS authentication method.

Option A is false because RADIUS does support accounting , and UDP port 1813 is commonly used for that purpose. Option B is false because a separate authorization server IP is not strictly required in this context; RADIUS can carry authorization attributes together with authentication/accounting processing depending on server behavior and device configuration. Option C is false because standard RADIUS communication uses UDP , not TCP, with authentication typically on port 1812 and accounting on 1813 . HCIA-Datacom teaches domain-based AAA processing as a key concept, where the user name suffix determines which authentication, authorization, and accounting policies are applied on the NAS device.