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Question 121. On Huawei devices, how is route preference interpreted when multiple routing protocols provide routes to the same destination?

1. A larger preference value always indicates a better route
2. A smaller preference value indicates a higher route priority
3. Preference is considered only for BGP routes
4. Preference has no effect on route selection

Correct Answer: 2. A smaller preference value indicates a higher route priority

Explanation:

Huawei devices use route preference to compare routes learned through different routing protocols or configured by different methods. When multiple routes to the same destination are available from different protocol sources, the route with the smaller preference value has the higher priority and is normally selected. For example, direct routes have a very high priority because their preference is lower than ordinary dynamic or static routes. Preference should not be confused with a routing protocol’s internal metric. Metrics compare routes within a protocol, whereas preference helps compare routes learned from different sources.

Question 122. What is the default preference of a typical IPv4 static route on Huawei devices when no preference is explicitly configured?

1. 0
2. 10
3. 255
4. 60

Correct Answer: 4. 60

Explanation:

Huawei documentation specifies a default preference of 60 for a standard IPv4 static route when the administrator does not manually configure another value. Because a smaller preference value represents a higher route priority, administrators can manipulate the preference to control whether a static route should be primary or act as a backup. Static routes support configurable preference values from 1 through 255 on relevant Huawei platforms. Understanding this behavior is important for designing floating static routes and for troubleshooting cases in which a static route unexpectedly wins or loses against a route learned through a dynamic routing protocol.

Question 123. What is a floating static route?

1. A static route configured with a less preferred preference value so it is used mainly when the primary route disappears
2. A static route that automatically changes its destination prefix
3. A static route that can only be installed in an MPLS VPN
4. A route learned dynamically through BGP

Correct Answer: 1. A static route configured with a less preferred preference value so it is used mainly when the primary route disappears

Explanation:

A floating static route is normally configured as a backup route by assigning it a preference that makes it less attractive than the primary route. While the preferred dynamic or static route remains available, the floating route does not become the selected forwarding path. If the primary route is withdrawn, the backup static route can then enter the routing table. Because Huawei uses smaller preference values for more preferred routes, a floating static route generally uses a numerically larger preference than the primary route. This is a simple and useful method of providing backup connectivity in networks with predictable topology.

Question 124. What is the PRIMARY benefit of associating BFD with a static route?

1. It automatically converts the route into OSPF
2. It prevents static routes from using next hops
3. It allows rapid detection of forwarding-path failure so the static route can be removed from the routing table
4. It automatically changes the route’s destination prefix

Correct Answer: 3. It allows rapid detection of forwarding-path failure so the static route can be removed from the routing table

Explanation:

Static routes do not inherently have a dynamic neighbor or failure-detection mechanism. By associating a static route with Bidirectional Forwarding Detection, the device can monitor whether the path associated with that route remains operational. Huawei documents that when the bound BFD session goes Down, the device can remove the static route from the IP routing table. When the BFD session returns Up, the route can be installed again. This allows static routing to react much more quickly to failures than relying only on manual intervention or slow indirect failure detection.

Question 125. When a BFD session associated with a Huawei static route transitions to Down because of a link failure, what happens to the route?

1. The static route is removed from the IP routing table
2. The route is automatically converted to a default route
3. The preference changes to 0
4. The route becomes an OSPF external route

Correct Answer: 1. The static route is removed from the IP routing table

Explanation:

Huawei’s BFD-for-static-route mechanism makes route installation dependent on the BFD session state. If BFD detects that the monitored forwarding path has failed and the session enters the Down state, the device removes the corresponding static route from the IP routing table. This permits another valid route to take over forwarding if one exists. When BFD later detects that the path has recovered and the session becomes Up again, the static route can be reinstalled. This linkage improves reliability because a configured next hop is not assumed to remain reachable simply because the local interface remains physically Up.

Question 126. What is a key difference between single-hop and multi-hop BFD detection for static routes?

1. Multi-hop BFD is only for Layer 2 switching
2. Single-hop BFD never uses a peer address
3. Multi-hop BFD requires the peer to be on the same Ethernet segment
4. Single-hop BFD monitors a directly connected next hop, whereas multi-hop BFD can monitor a recursively reachable next hop

Correct Answer: 4. Single-hop BFD monitors a directly connected next hop, whereas multi-hop BFD can monitor a recursively reachable next hop

Explanation:

Huawei distinguishes between single-hop and multi-hop BFD when monitoring static routes. In single-hop mode, the configured next hop is directly connected, and the associated outbound interface and peer address can be used directly. Multi-hop BFD is appropriate when the static route’s original next hop is not directly connected and must be recursively resolved through another route. This flexibility allows BFD to monitor both directly connected backup paths and more complex recursive static routes. Selecting the correct BFD mode is important because the expected forwarding and adjacency relationships differ between the two designs.

Question 127. What is the PRIMARY purpose of tracking a static route with NQA?

1. To create VLANs dynamically
2. To determine whether a remote destination or service path is reachable and withdraw the static route when the monitored path fails
3. To elect an OSPF DR
4. To generate BGP attributes

Correct Answer: 2. To determine whether a remote destination or service path is reachable and withdraw the static route when the monitored path fails

Explanation:

Huawei supports associating static routes with Network Quality Analysis (NQA) so the device can monitor actual reachability rather than assuming a route is valid simply because the outbound interface is Up. NQA can perform probes toward a remote destination, and the route’s availability can depend on the monitoring result. This is useful when a failure occurs beyond the directly connected next hop. BFD is typically focused on fast forwarding-path liveliness, while NQA can provide broader service or destination testing. Both mechanisms improve static-route reliability compared with ordinary static routing alone.

Question 128. What does Equal-Cost Multi-Path (ECMP) routing provide?

1. Only one usable path to each destination
2. A mechanism that disables redundant routes
3. The ability to install and use multiple equal-cost routes toward the same destination
4. Automatic NAT translation across all routes

Correct Answer: 3. The ability to install and use multiple equal-cost routes toward the same destination

Explanation:

ECMP allows a router to maintain multiple equally preferred paths to the same destination and distribute traffic across them according to the device’s forwarding algorithm. This can increase aggregate bandwidth usage and provide resilience if one path fails. The routes generally need to be considered equally optimal according to the routing protocol or route-selection process. ECMP is different from a floating backup route, which is intentionally less preferred and remains unused until a primary route fails. With ECMP, multiple routes can participate in forwarding at the same time.

Question 129. What is the primary purpose of a default route?

1. To provide a forwarding path for destinations that do not match a more specific route
2. To override every more-specific route
3. To advertise multicast membership
4. To create an MPLS label automatically

Correct Answer: 4. To provide a forwarding path for destinations that do not match a more specific route

Explanation:

A default route acts as a route of last resort. When the routing table contains no more-specific match for a packet’s destination, the default route can direct the traffic toward an upstream next hop or exit interface. In IPv4, the default prefix is 0.0.0.0/0. Longest-prefix matching ensures that more-specific routes take precedence over the default route. Default routes are widely used at branch offices, Internet edges, and simple networks where maintaining every remote prefix individually is unnecessary. Huawei static routing supports default static routes as a standard routing feature.

Question 130. Why can a static route remain installed even when a remote destination is unreachable several hops beyond the configured next hop?

1. A basic static route has no built-in dynamic mechanism to detect every remote path failure
2. Static routes always perform NQA automatically
3. Static routes automatically run BFD without configuration
4. The router ignores next-hop reachability entirely

Correct Answer: 1. A basic static route has no built-in dynamic mechanism to detect every remote path failure

Explanation:

Traditional static routing is simple and predictable, but the router does not inherently exchange protocol messages to determine whether the complete remote path remains healthy. If the local interface and next-hop resolution remain valid, a static route can stay installed even when a failure exists farther away in the network. Huawei specifically introduces BFD and NQA tracking to improve this limitation. BFD can monitor forwarding liveliness quickly, while NQA can probe remote reachability or service quality. These mechanisms make static routing more responsive to failures that ordinary route configuration cannot detect directly.

Question 131. In multicast routing, what is the PRIMARY function of a Rendezvous Point (RP) in PIM-SM?

1. It serves as a shared meeting point used when multicast sources and receivers initially build shared-tree connectivity
2. It assigns IPv6 addresses to receivers
3. It replaces IGMP on end hosts
4. It operates as the STP root bridge

Correct Answer: 3. It serves as a shared meeting point used when multicast sources and receivers initially build shared-tree connectivity

Explanation:

PIM Sparse Mode uses a Rendezvous Point as a logical meeting point for multicast sources and receivers, especially during initial shared-tree establishment. Receivers can join toward the RP, and source information can also be registered toward the RP. Depending on the implementation and traffic conditions, routers may later switch to source-specific shortest-path trees. RPs can be configured statically or dynamically. Huawei PIM-SM examples show both static RP configuration and dynamic RP election using candidate RPs and a Bootstrap Router mechanism.

Question 132. Which multicast model allows receivers to specify both the multicast group and the exact source they want to receive from?

1. ASM only
2. Source-Specific Multicast (SSM)
3. Broadcast multicast
4. MPLS multicast only

Correct Answer: 2. Source-Specific Multicast (SSM)

Explanation:

Source-Specific Multicast lets a receiver express interest in traffic from a particular source and multicast group combination, commonly represented as an (S,G) channel. Because the source is already known, SSM avoids the need for some of the source-discovery and shared-tree mechanisms required by Any-Source Multicast. Huawei PIM-SM configurations can define an SSM group address range using an SSM policy. SSM is particularly useful for applications such as IPTV or controlled content distribution where receivers know which source they expect to use.

Question 133. Which multicast model normally allows receivers to join a group without specifying the source in advance?

1. Any-Source Multicast (ASM)
2. SSM only
3. Unicast multicast
4. LDP multicast

Correct Answer: 1. Any-Source Multicast (ASM)

Explanation:

In Any-Source Multicast, receivers join a multicast group without necessarily knowing which source will transmit to that group. PIM-SM commonly supports this model by using an RP to help sources and receivers discover one another. SSM differs because the receiver explicitly specifies the desired source and group combination. The two models therefore have different control-plane requirements. Understanding ASM and SSM helps when troubleshooting why a multicast receiver receives no traffic even though IGMP membership exists; the configured PIM and source-discovery model must match the application design.

Question 134. What is a multicast static route primarily used for?

1. To create a default unicast gateway
2. To determine DHCP server reachability
3. To elect a PIM RP
4. To influence the route used for multicast RPF checks independently of the ordinary unicast forwarding path**

Correct Answer: 4. To influence the route used for multicast RPF checks independently of the ordinary unicast forwarding path

Explanation:

A multicast static route can alter the route that a multicast device uses for its Reverse Path Forwarding check. Huawei provides examples in which an ip rpf-route-static entry deliberately selects an RPF neighbor different from the one implied by normal unicast routing. This can be useful when the desired multicast distribution path should differ from the unicast path. Because RPF determines whether multicast packets arrived on the correct upstream interface, modifying the RPF route changes the upstream direction that multicast forwarding considers valid.

Question 135. In PIM-SM dynamic RP discovery, what is the role of a Bootstrap Router (BSR)?

1. To distribute candidate RP information within the PIM-SM domain
2. To assign IP addresses to multicast receivers
3. To act as an Ethernet root bridge
4. To perform NAT for multicast sources

Correct Answer: 2. To distribute candidate RP information within the PIM-SM domain

Explanation:

In a dynamic PIM-SM RP environment, Candidate RPs advertise their availability, and the Bootstrap Router participates in distributing RP-set information throughout the PIM domain. Routers can then determine which RP should serve particular multicast groups according to the dynamic mechanism. Huawei configuration examples show devices configured as Candidate BSR and Candidate RP, allowing RP information to be learned dynamically rather than manually configuring a static RP on every router. This improves manageability in larger multicast domains.

Question 136. What is the main purpose of WLAN WPA2 or WPA3 security?

1. To provide authentication and encryption for wireless client traffic
2. To elect an OSPF router ID
3. To establish BGP sessions
4. To provide DHCP relay

Correct Answer: 3. To provide authentication and encryption for wireless client traffic

Explanation:

WPA-family security mechanisms are designed to protect wireless LAN access and traffic. They provide authentication so unauthorized users cannot simply join the WLAN and encryption so captured over-the-air frames are not readable in plain text. Enterprise WLANs can combine strong wireless encryption with centralized authentication, such as 802.1X and AAA services. WLAN security is particularly important because radio transmissions extend beyond physical walls, meaning attackers may be able to reach the wireless medium without entering the building. Huawei’s H12-821 scope includes both WLAN and network security as core datacom topics.

Question 137. Why is 802.1X commonly used with enterprise WLAN security?

1. It provides user or device authentication before normal network access is granted
2. It creates MPLS labels
3. It replaces wireless encryption entirely
4. It provides VRRP gateway redundancy

Correct Answer: 4. It provides user or device authentication before normal network access is granted

Explanation:

802.1X provides port- or access-based authentication using an authentication framework such as EAP together with a backend AAA server. In enterprise WLANs, it is commonly combined with WPA2-Enterprise or WPA3-Enterprise so each user or device authenticates individually rather than everyone sharing one pre-shared key. Authentication determines whether the endpoint should be granted network access, while the WPA mechanism provides the wireless encryption and keying framework. This separation improves accountability and allows administrators to centrally revoke access for individual users or devices without changing a shared WLAN password.

Question 138. What is a significant operational disadvantage of using one pre-shared WLAN key for a large employee population?

1. The key cannot encrypt wireless traffic
2. A single shared secret is difficult to revoke for one user without changing it for everyone
3. It prevents APs from transmitting beacons
4. It automatically disables roaming

Correct Answer: 2. A single shared secret is difficult to revoke for one user without changing it for everyone

Explanation:

A pre-shared key is simple to configure, but it scales poorly when many users share the same credential. If one employee leaves or the key is disclosed, administrators must generally change the shared key and redistribute the replacement to all legitimate users and devices. Individual accountability is also weaker because many clients authenticate with the same secret. Enterprise 802.1X-based authentication provides a better model for large organizations by giving users or devices distinct identities and allowing access to be revoked centrally without changing credentials for the entire WLAN.

Question 139. What is the PRIMARY purpose of control-plane protection mechanisms such as CPCAR on Huawei network devices?

1. To protect CPU resources from excessive protocol or attack traffic
2. To increase the number of uncontrolled packets reaching the CPU
3. To disable all routing protocols
4. To replace data-plane QoS

Correct Answer: 1. To protect CPU resources from excessive protocol or attack traffic

Explanation:

Network-device CPUs process routing protocols, management traffic, exception packets, and other control-plane functions. If excessive traffic is punted to the CPU, critical protocol processing can be delayed or the device can become unstable. Huawei uses mechanisms such as CPCAR to rate-limit and prioritize traffic sent to the CPU. Important protocol traffic can receive more favorable treatment, while excessive or low-priority packets can be limited or discarded. Control-plane protection therefore contributes both to security and network reliability during attacks, traffic storms, or protocol abnormalities.

Question 140. A branch has two WAN paths. The primary path should be used normally, the backup should activate when remote reachability fails, voice should use the path with acceptable delay and jitter, and multicast receivers should receive traffic only from a known source. Which design BEST meets these requirements?

1. Configure only one static route and PIM-ASM
2. Use STP to select WAN paths and IGMP for voice QoS
3. Use a preferred route plus a floating static backup tracked by BFD/NQA, use quality measurements or Smart Policy Routing for voice, and use SSM for known-source multicast
4. Use only DHCP and VRRP

Correct Answer: 3. Use a preferred route plus a floating static backup tracked by BFD/NQA, use quality measurements or Smart Policy Routing for voice, and use SSM for known-source multicast

Explanation:

The design combines technologies according to their strengths. A primary route plus a higher-preference-value floating static route provides simple backup routing. BFD or NQA can detect path failure so an unusable route is withdrawn rather than remaining installed. Smart Policy Routing can evaluate quality metrics such as delay, jitter, and packet loss to steer voice toward a suitable WAN path. Finally, Source-Specific Multicast is appropriate when receivers know the exact multicast source they require. This combination addresses reliability, application quality, and multicast-control requirements without relying on one protocol to solve unrelated problems.