• Home
• Huawei Exams
• H12-811 - HCIA-Datacom V1.0

H12-811 Huawei Practice Test Questions and Exam Dumps

Question No 1:

In the context of Spanning Tree Protocol (STP), each switch port is assigned a cost value that reflects the overhead or expense of using that port to forward traffic within the network topology. This cost plays a critical role in determining the best path to the root bridge during the formation of a loop-free Layer 2 topology. The default cost value of a port is determined based on its bandwidth.

Which of the following best describes the default relationship between a port's bandwidth and its associated STP port cost?

A. Ports with higher bandwidth are assigned lower STP costs.
B. Ports with higher bandwidth are assigned higher STP costs.
C. A port’s STP cost is numerically equal to its bandwidth in Mbps.
D. The STP port cost is assigned randomly and does not follow any predictable pattern.

Correct Answer: A. Ports with higher bandwidth are assigned lower STP costs.

Explanation:

Spanning Tree Protocol (STP) is used in Layer 2 networks to prevent loops by creating a loop-free logical topology. During STP calculations, each switch assigns a cost to its ports, known as the port cost, which represents the relative expense of sending traffic over that interface. The total cost of a path to the root bridge is the sum of the individual port costs along that path. STP uses these costs to determine the most efficient, lowest-cost path from each switch to the root bridge.

By default, the port cost is inversely proportional to the port’s bandwidth. That means higher-bandwidth links are considered more desirable and are assigned lower costs, encouraging STP to favor these links in the active topology. For example, a 10 Mbps port might have a default cost of 100, a 100 Mbps port might have a cost of 19, and a 1 Gbps port might be assigned a cost of 4. These values can be manually adjusted by administrators to influence STP decisions, but the default behavior always prefers faster links due to their lower cost.

Understanding this relationship is critical in network design, especially in scenarios involving redundant links of differing speeds. Incorrect assumptions about port costs can lead to suboptimal STP topologies where slower links are preferred over faster ones, reducing overall network efficiency. Therefore, knowing that a higher port bandwidth results in a lower STP port cost is fundamental to managing STP effectively in enterprise networks.

Question No 2:

In a routing table, when the protocol of a route is displayed as OSPF (Open Shortest Path First), the preference or administrative distance associated with the route is fixed. 

What is the default administrative distance (preference) for OSPF routes, and how does it affect the routing table?

A. True
B. False

Answer: B. False

Explanation:

In networking, routing protocols use an administrative distance (AD) to determine the trustworthiness of a route. The administrative distance is a value that is assigned to a route, and it helps the router decide which route to prefer when multiple routing protocols provide routes to the same destination. The lower the AD, the more preferred the route.

For OSPF (Open Shortest Path First), the default administrative distance is 110, not 10. This means that if a router learns about the same destination from multiple routing protocols, and one is OSPF while the other could be a protocol with a lower AD (such as directly connected routes with an AD of 0, or static routes with an AD of 1), the router will prefer the route with the lower AD value.

To clarify, OSPF's default administrative distance of 110 ensures that it has a relatively lower priority compared to more direct methods like static routes (AD 1) or directly connected networks (AD 0). However, OSPF is more preferred than other protocols like RIP (Routing Information Protocol), which has an AD of 120.

The value of 10 mentioned in the question might be mistakenly associated with a different routing protocol. For instance, in Cisco systems, EIGRP (Enhanced Interior Gateway Routing Protocol) has a default administrative distance of 90, and OSPF remains at 110.

The administrative distance can be modified manually by network administrators to influence routing decisions. For example, if an administrator wants OSPF to be preferred over other protocols, they might change the AD of OSPF or the other routing protocols.

In summary, the statement in the question is false, as the default administrative distance for OSPF is 110, not 10.

Question No 3:

Which of the following protocols is not typically used for file transfer?

A. FTP
B. TFTP
C. SFTP
D. HTTP

Detailed Question with Answer and Explanation:

Question:

File transfer protocols are essential in computer networking to facilitate the transfer of files between different systems across a network. These protocols enable the reliable, secure, and efficient transmission of data. In the list below, 

Which of the given protocols is not primarily designed for file transfer?

Options:

• A. FTP (File Transfer Protocol)

• B. TFTP (Trivial File Transfer Protocol)

• C. SFTP (Secure File Transfer Protocol)

• D. HTTP (Hypertext Transfer Protocol)

Answer: D. HTTP (Hypertext Transfer Protocol)

Explanation:

File transfer protocols are designed specifically to manage the sending, receiving, and storing of files over a network. Among the options listed, three are primarily used for file transfer, while one, HTTP, is not.

1. FTP (File Transfer Protocol):
   FTP is a standard network protocol used to transfer files between a client and a server over a TCP/IP network. It is one of the oldest and most widely used protocols for file transfer and offers features like user authentication, the ability to transfer large files, and support for directories. FTP operates over ports 20 and 21, where port 21 is used for the control connection, and port 20 for data transfer.
   
   

2. TFTP (Trivial File Transfer Protocol):
   TFTP is a simpler, lightweight version of FTP. It does not offer authentication or encryption, and it is primarily used in scenarios where ease of use and low overhead are important, such as network booting or transferring configuration files between devices. TFTP operates over UDP (User Datagram Protocol), typically using port 69.
   
   

3. SFTP (Secure File Transfer Protocol):
   SFTP is a secure version of FTP. It operates over SSH (Secure Shell) to encrypt the data during transfer, making it much safer than FTP or TFTP. It is used for secure file transfer and provides features such as encryption, secure authentication, and data integrity verification.
   
   

4. HTTP (Hypertext Transfer Protocol):
   HTTP, while widely used for accessing and transmitting web pages over the internet, is not a file transfer protocol in the traditional sense. It is primarily designed for requesting and delivering web content, such as HTML files, images, and videos, from a server to a client. Although files can be transferred over HTTP (such as downloading or uploading files via web forms), it is not designed specifically for general-purpose file transfers. HTTP typically operates over port 80 and, when encrypted (HTTPS), over port 443.

Thus, the correct answer is D. HTTP, as it is primarily a web communication protocol, not specificaly a file transfer protocol like FTP, TFTP, or SFTP.

Question No 4:

When a switch port receives a frame that does not contain a VLAN tag, it must add a Port VLAN ID (PVID) to the frame in order to identify the VLAN to 

Which the frame belongs. Is this statement true or false?

A. True
B. False

Answer: A. True

Explanation:

In Ethernet networks, VLANs (Virtual Local Area Networks) are used to segment a physical network into multiple logical networks. These VLANs are identified by VLAN tags, which are added to Ethernet frames to denote which VLAN the frame belongs to. The VLAN tag is part of the IEEE 802.1Q standard, where it is inserted into the Ethernet frame’s header. However, not all frames arriving at a switch port are necessarily tagged.

When a frame arrives at a switch port that does not carry a VLAN tag (known as an untagged frame), the switch needs a method to determine which VLAN the frame should be associated with. This is where the Port VLAN ID (PVID) comes into play. The PVID is a value that a switch port is configured with to handle untagged frames. When an untagged frame arrives at a port, the switch uses the PVID assigned to that port to tag the frame with the appropriate VLAN ID. This ensures that the frame is placed into the correct VLAN for further processing and delivery.

For example, if a switch port is configured with a PVID of VLAN 10 and an untagged frame arrives on that port, the switch will add the VLAN tag with VLAN ID 10 to the frame before forwarding it. This helps maintain proper VLAN segregation within the network.

The PVID concept is crucial for maintaining the integrity of VLANs in networks, particularly in environments where devices may not be capable of adding VLAN tags to their frames, such as older devices or some user-facing devices like computers or printers.

In summary, when a switch port receives an untagged frame, it must add the PVID to the frame to ensure proper VLAN identification and handling. Therefore, the statement is True.

Question No 5:

What are the advantages of inter-VLAN routing when implemented in one-arm routing mode? Select all that apply.

A. Reduced number of links
B. Reduced use of IP addresses
C. Reduced number of devices
D. Reduced number of entries in the routing table

Detailed Question with Answer and Explanation:

Answer:

The correct advantages of inter-VLAN routing in one-arm routing mode are:

• A. Reduced number of links

• B. Reduced use of IP addresses

• C. Reduced number of devices

Explanation:

One-arm routing mode is a configuration where a router handles inter-VLAN communication while only using a single physical link between the router and a switch. This approach offers several key advantages over traditional routing methods, which may require more complex setups. Let’s break down the benefits:

1. Reduced Number of Links (A):
   In one-arm routing mode, a single physical interface on the router is used to handle traffic between multiple VLANs. The router has multiple sub-interfaces (logical interfaces) on the same physical interface. This means there is only one physical link required between the router and the switch, as opposed to traditional routing, where each VLAN may need a separate link to the router. This reduces the overall cabling and infrastructure required.
   
   

2. Reduced Use of IP Addresses (B):
   Since a single physical interface is used to handle multiple VLANs, there is no need to assign a separate IP address to each VLAN on different physical interfaces. Instead, the router uses sub-interfaces, each assigned a unique IP address that corresponds to a specific VLAN. Therefore, the need for numerous IP addresses is minimized, making network management more efficient.
   
   

3. Reduced Number of Devices (C):
   One-arm routing eliminates the need for multiple physical routers or additional routing devices. Instead of deploying separate routers for each VLAN, a single router (with sub-interfaces) is sufficient to handle the traffic for all VLANs. This reduces the overall number of devices in the network, lowering hardware costs and simplifying network management.
   
   

4. Reduced Number of Entries in the Routing Table (D):
   This option is not generally applicable. The number of entries in the routing table is typically determined by the number of subnets or networks in the routing domain, not by the mode of inter-VLAN routing. Whether using one-arm routing or traditional routing, the number of entries will still be proportional to the number of VLANs and their respective subnets.

In summary, one-arm routing mode enhances network efficiency by minimizing physical infrastructure and simplifying network configuration, leading to reduced links, fewer IP addresses, and fewer devices.

Question No 6:

Can trunk interfaces send both tagged and untagged frames?

A. True
B. False

Answer: A. True

Explanation:

A trunk interface is a type of network interface in a switch that allows multiple VLANs (Virtual Local Area Networks) to communicate over a single physical connection. This is typically used to connect network devices like switches or routers, enabling them to carry traffic from multiple VLANs simultaneously. Trunking is achieved by tagging frames with VLAN information.

1. Tagged Frames: When traffic is sent over a trunk interface, the frames that belong to specific VLANs are tagged with a VLAN ID. This allows the receiving device to identify the VLAN to which the frame belongs. The tag, which adheres to the IEEE 802.1Q standard, is inserted into the Ethernet frame header. This tagging ensures that each frame is properly directed to the correct VLAN on the receiving side. Tagged frames are used for inter-VLAN communication across trunk links between switches or between a switch and a router.
   
   

2. Untagged Frames: However, trunk interfaces can also carry untagged frames, particularly when a frame originates from a device that is connected to an access port (a port assigned to a single VLAN). If an untagged frame arrives at a trunk port, the trunk port assigns it to a default VLAN. This is the VLAN configured as the native VLAN on the trunk link. The native VLAN is a special VLAN where frames are transmitted without a VLAN tag. For example, on many switches, VLAN 1 is the default native VLAN, meaning frames on this VLAN will be untagged when transmitted over the trunk.

In summary, trunk interfaces are designed to handle both tagged and untagged frames. The tagged frames allow for multiple VLANs to be transmitted, while untagged frames are assigned to the native VLAN and allow for backward compatibility with devices that do not support VLAN tagging. This flexibility is essential for maintaining network compatibility and supporting multiple VLANs in diverse network setups.

Question No 7:

Does IEEE 802.11ac support only the 5 GHz frequency band?

A. True
B. False

Answer: B. False

Explanation:

The IEEE 802.11ac standard, often referred to as Wi-Fi 5, is primarily designed to operate on the 5 GHz frequency band, which allows for higher data rates, improved bandwidth, and reduced interference. However, it is not restricted to only the 5 GHz band. While the 802.11ac standard uses the 5 GHz band for high-speed wireless communication, it is compatible with both the 2.4 GHz and 5 GHz frequency bands, though the 2.4 GHz band is more commonly used with older Wi-Fi standards (such as 802.11b/g/n).

In practice, 802.11ac is predominantly used in the 5 GHz band because it offers significantly more non-overlapping channels compared to the 2.4 GHz band. The 2.4 GHz band is crowded with devices like microwaves, Bluetooth devices, and older Wi-Fi standards, which can cause interference and slow down network performance. The 5 GHz band, in contrast, provides more available channels and less interference, making it more suitable for high-speed data transmission.

It is also important to note that 802.11ac supports several advanced features such as wider channel bandwidths (20 MHz, 40 MHz, 80 MHz, and even 160 MHz), multiple spatial streams, and advanced modulation techniques that enhance performance in the 5 GHz band. As a result, 802.11ac devices often prioritize the 5 GHz band to maximize performance and reliability.

In some cases, devices that support dual-band operation (both 2.4 GHz and 5 GHz) can switch between the bands depending on the network conditions, providing users with greater flexibility. Therefore, the IEEE 802.11ac standard is capable of operating in both the 2.4 GHz and 5 GHz frequency bands, though its primary advantages are realized in the 5 GHz band.

Question No 8:

Which of the following protocols is designed to prevent loops in a Layer 2 network that has redundant links?

A. VRRP
B. STP
C. ARP
D. UDP

Answer: B. STP (Spanning Tree Protocol)

Explanation:

In a Layer 2 network, switches are responsible for forwarding frames based on MAC addresses. When multiple paths exist between two devices, there is a potential for network loops. A network loop occurs when data packets circulate endlessly through the network, leading to broadcast storms, network congestion, and even network failures. To prevent this, a protocol that controls redundant paths is essential.

The Spanning Tree Protocol (STP) is specifically designed to prevent loops in a Layer 2 network with redundant links. STP is a link management protocol that ensures a loop-free topology by dynamically blocking certain redundant links and only allowing one active path between any two devices. STP is based on the IEEE 802.1D standard and uses an algorithm that elects a root bridge and computes the shortest path to that root from all other bridges (switches) in the network.

In a typical STP-enabled network, redundant paths are initially placed in a blocking state. If the active path fails (e.g., due to a link failure), the STP protocol automatically recalculates and places an alternative path into the forwarding state, ensuring continuous connectivity without loops. The protocol also uses timers to recheck the topology and dynamically adjust the active paths in case of network changes.

Now, let’s briefly look at the other options:

• A. VRRP (Virtual Router Redundancy Protocol): This protocol is used for providing high availability and redundancy at the IP layer (Layer 3). It allows multiple routers to work together, with one router acting as the primary gateway. However, VRRP does not address Layer 2 loop prevention.

• C. ARP (Address Resolution Protocol): ARP is used to map an IP address to a MAC address in a local network. It does not serve the purpose of preventing loops.

• D. UDP (User Datagram Protocol): UDP is a transport-layer protocol used for sending datagrams across a network. It does not provide any mechanism for preventing Layer 2 loops.

Thus, STP is the correct protocol for preventing loops in a Layer 2 network with redundant links, ensuring smooth and reliable network operation.

Question No 9:

Which of the following types of packets are part of the OSPF (Open Shortest Path First) protocol?

A. HELLO
B. LSR
C. LSU
D. LSA

Answer:
A. HELLO
B. LSR
C. LSU

Explanation:

OSPF (Open Shortest Path First) is a widely used interior gateway protocol that helps in the exchange of routing information within an autonomous system. It uses various types of packets to maintain and update its routing tables and ensure network reachability. These packets are crucial for the OSPF process, as they allow routers to exchange information, discover neighbors, and maintain an up-to-date routing table.

Here’s a breakdown of each packet type mentioned in the question:

1. HELLO Packets (A):
   HELLO packets are used by OSPF routers to discover and establish neighbors. Routers send HELLO packets on OSPF-enabled interfaces to identify other OSPF routers in the same network segment. These packets help routers determine which neighbors are up and reachable, allowing them to exchange routing information. Additionally, HELLO packets are also used to verify OSPF router parameters, such as the area ID and router authentication information.
   
   

2. LSR (Link-State Request) Packets (B):
   LSR packets are used when a router requests specific pieces of link-state information from a neighboring router. These packets are typically sent when a router has detected that its link-state database (LSDB) is out of sync with the rest of the network. When a router receives an LSR packet, it will respond with an LSU packet (explained below) containing the requested link-state advertisements (LSAs).
   
   

3. LSU (Link-State Update) Packets (C):
   LSU packets are used to send updates containing LSAs between OSPF routers. These packets are sent in response to an LSR request or during regular LSDB synchronization. LSU packets carry information about changes in the network topology, including new routes, network states, or changes in link status. When a router receives an LSU, it updates its LSDB with the new information and recalculates its SPF (Shortest Path First) tree.
   
   

4. LSA (Link-State Advertisement) (D):
   LSA is not a packet type but rather the information carried within LSU packets. LSAs are advertisements that describe the state of a router's links and provide detailed information about the topology of the network. These LSAs are exchanged among OSPF routers to help them build a synchronized LSDB, which is crucial for the SPF algorithm to work properly.

In summary, the OSPF protocol uses HELLO, LSR, and LSU packets to communicate between routers and maintain an accurate and up-to-date network topology, while LSA refers to the information that is encapsulated in LSU packets.