View Full Huawei H12-831 Exam Dumps and Practice Test Dumps

 

Question 301.

In OSPF, what is the main purpose of an external Type 1 metric?

1. Calculate the route using both the external metric and the internal OSPF cost to reach the ASBR
2. Ignore all internal OSPF costs
3. Select the DR on a broadcast network
4. Identify an MPLS VPN

Correct Answer: 1. Calculate the route using both the external metric and the internal OSPF cost to reach the ASBR

Explanation:

An OSPF external Type 1 route considers both the external metric assigned when the route enters OSPF and the internal OSPF cost required to reach the ASBR. This means the total cost can differ depending on where a router is located inside the OSPF domain. E1 routes are useful when internal path cost should influence selection among multiple external exits. This differs from E2 behavior, where the external metric is normally the dominant value.

Question 302.

How does an OSPF external Type 2 route primarily differ from an external Type 1 route?

1. E2 routes cannot be advertised by an ASBR
2. The external metric is primarily used, with internal cost generally serving only as a later distinction when needed
3. E2 routes are limited to Area 0
4. E2 routes require BGP

Correct Answer: 2. The external metric is primarily used, with internal cost generally serving only as a later distinction when needed

Explanation:

OSPF E2 routes generally retain the external metric assigned by the ASBR as the principal metric throughout the OSPF domain. Internal cost to reach the ASBR does not simply add to that external value in the same way it does for an E1 route. As a result, E2 can be useful when administrators want the external metric to remain consistent across the domain. Choosing between E1 and E2 depends on how much internal topology should influence external path selection.

Question 303.

What is the main effect of configuring OSPF on a point-to-point link?

1. A DR and BDR must always be elected
2. The link automatically becomes Area 0
3. OSPF can form a direct adjacency without DR or BDR election
4. The link can carry only external routes

Correct Answer: 3. OSPF can form a direct adjacency without DR or BDR election

Explanation:

A point-to-point OSPF network connects two routers directly, so there is no need for a Designated Router or Backup Designated Router. The two routers can establish a direct adjacency and exchange routing information without the multi-access optimization used on broadcast networks. Correctly configuring the network type helps avoid unnecessary election behavior and ensures timers and adjacency logic match the physical or logical topology of the link.

Question 304.

Which OSPF election rule applies when two eligible routers on the same broadcast segment have equal interface priorities?

1. The router with the lowest OSPF cost wins automatically
2. The router with the lowest IP address becomes DR
3. The router with the shortest AS_Path wins
4. The router with the higher Router ID is preferred**

Correct Answer: 4. The router with the higher Router ID is preferred

Explanation:

During OSPF DR and BDR election, interface priority is considered first. If eligible routers have the same priority, the Router ID is used as the tiebreaker, with the higher Router ID preferred. Administrators can influence the election more predictably by explicitly configuring interface priorities rather than relying on Router IDs. The election process is specific to multi-access OSPF networks and has no relationship to BGP AS_Path or ordinary route cost.

Question 305.

Which BGP attribute is commonly used to group routes for scalable routing policy?

1. Community
2. Router ID
3. Hold timer
4. TCP port

Correct Answer: 1. Community

Explanation:

BGP communities allow routes to be tagged with values that can later be matched by routing policies. Instead of maintaining a separate rule for every individual prefix, an administrator can assign the same community to related routes and apply a common action. Communities are widely used for Local Preference changes, controlled advertisement, blackholing policies, and service-provider traffic engineering. They provide policy metadata and do not replace the destination prefix or the BGP transport session.

Question 306.

Why is next-hop reachability important when evaluating a BGP route?

1. It determines the BGP autonomous system number
2. A route normally cannot be used for forwarding if its BGP Next_Hop cannot be resolved
3. It controls VRRP priority
4. It creates MPLS labels automatically

Correct Answer: 2. A route normally cannot be used for forwarding if its BGP Next_Hop cannot be resolved

Explanation:

A router may receive a BGP route and its associated attributes, but the route is not normally usable unless the Next_Hop address can be resolved through the routing table. In iBGP networks, this often means the IGP must provide reachability to external or loopback next-hop addresses. If that recursive reachability is missing, the BGP path may remain unusable even if its other attributes appear preferable.

Question 307.

What is the primary benefit of applying a route policy to routes before advertising them to a BGP peer?

1. Increase physical link bandwidth
2. Eliminate TCP from BGP
3. Control which routes and attributes are presented to that peer
4. Replace the peer’s AS number

Correct Answer: 3. Control which routes and attributes are presented to that peer

Explanation:

Outbound BGP policies allow administrators to determine exactly which routes should be advertised and how their attributes should appear. A policy can permit or deny selected prefixes, attach communities, alter MED, or perform other supported actions. This makes routing behavior more predictable and helps prevent accidental route leaks. Well-designed outbound policy is particularly important on external BGP boundaries where incorrect advertisements can affect networks beyond the local organization.

Question 308.

Which statement BEST describes the relationship between eBGP and iBGP?

1. Both are used only inside one autonomous system
2. eBGP cannot exchange internet routes
3. iBGP always uses directly connected peers
4. eBGP exchanges routes between autonomous systems, while iBGP distributes BGP routes within an autonomous system**

Correct Answer: 4. eBGP exchanges routes between autonomous systems, while iBGP distributes BGP routes within an autonomous system

Explanation:

eBGP is used between routers in different autonomous systems and is the foundation of inter-domain routing. iBGP operates between BGP speakers within the same autonomous system and distributes externally learned or internally originated BGP routes across that AS. The two modes follow different route-advertisement and path-handling rules. In large networks, iBGP commonly uses route reflectors to avoid the scaling burden of a full peer mesh.

Question 309.

In IS-IS, what does the ATT bit generally indicate to Level-1 routers?

1. A Level-1-2 router has connectivity toward the Level-2 domain
2. The DIS has failed
3. The router is overloaded
4. An MPLS label has expired

Correct Answer: 1. A Level-1-2 router has connectivity toward the Level-2 domain

Explanation:

The ATT, or Attached, indication is associated with Level-1-2 routers that provide connectivity from a Level-1 area toward the Level-2 backbone. Level-1 routers can use this information when determining how to reach destinations outside their own area. This supports the hierarchical nature of IS-IS, where Level-1 routers can maintain local-area topology while relying on appropriate Level-1-2 routers for broader connectivity.

Question 310.

Why is Level-2 continuity important in an IS-IS domain?

1. It determines host VLAN membership
2. It provides the backbone connectivity used for inter-area routing
3. It elects every DIS in the network
4. It assigns customer VPN labels

Correct Answer: 2. It provides the backbone connectivity used for inter-area routing

Explanation:

The Level-2 portion of an IS-IS network functions as the backbone for connectivity between different Level-1 areas. Level-1-2 routers connect local areas to this backbone. If Level-2 continuity is broken, inter-area reachability can be disrupted even though routing inside individual Level-1 areas may continue. A sound IS-IS design therefore ensures resilient Level-2 connectivity between the portions of the network that must exchange inter-area traffic.

Question 311.

What is the main purpose of a Forwarding Equivalence Class in MPLS?

1. Group packets that receive the same forwarding treatment
2. Identify an OSPF area
3. Determine VRRP mastership
4. Configure an Eth-Trunk

Correct Answer: 1. Group packets that receive the same forwarding treatment

Explanation:

A Forwarding Equivalence Class groups packets that should be handled in the same way by the MPLS forwarding plane. Packets in the same FEC may be mapped to the same label and forwarded along the same label-switched path or service context. This abstraction allows MPLS to separate packet classification from the forwarding actions performed by transit routers. FECs are a core concept behind label assignment and MPLS forwarding behavior.

Question 312.

What is the main difference between a PE router and a P router in an MPLS Layer 3 VPN?

1. A P router connects directly to customers, while a PE never does
2. A PE maintains customer VPN contexts, while a P router primarily forwards labeled traffic through the core
3. A P router runs only Layer 2 switching
4. A PE cannot participate in MPLS forwarding

Correct Answer: 2. A PE maintains customer VPN contexts, while a P router primarily forwards labeled traffic through the core

Explanation:

Provider Edge routers connect customer sites to the MPLS network and maintain VPN-specific routing contexts such as VRFs. They participate in VPN route distribution and apply service labels. Provider core P routers primarily transport labeled traffic between PE routers and generally do not maintain individual customer VPN routing tables. This division improves scalability because the provider core remains independent of most customer-specific routing information.

Question 313.

What does the inner label in a common MPLS Layer 3 VPN label stack usually represent?

1. The Ethernet source address
2. The OSPF Router ID
3. The customer VPN or service forwarding context
4. The BGP Hold timer

Correct Answer: 3. The customer VPN or service forwarding context

Explanation:

MPLS Layer 3 VPN traffic commonly uses two labels. The outer transport label carries the packet across the provider backbone toward the destination PE, while the inner label identifies the VPN or service context at that PE. When the packet arrives, the egress PE uses the inner label to determine the appropriate VRF or forwarding action. This layered label model enables the core to transport multiple customer VPNs efficiently without understanding all customer routes.

Question 314.

Which statement BEST describes the relationship between a Route Distinguisher and a Route Target?

1. Both perform exactly the same function
2. A Route Target uniquely identifies overlapping prefixes, while an RD sets VRRP priority
3. An RD determines LACP members, while a Route Target sets OSPF cost
4. An RD makes VPN prefixes unique, while a Route Target controls VPN route import and export**

Correct Answer: 4. An RD makes VPN prefixes unique, while a Route Target controls VPN route import and export

Explanation:

Route Distinguishers and Route Targets solve different problems in MPLS Layer 3 VPNs. The RD is combined with customer prefixes so overlapping addresses become unique VPN routes in MP-BGP. Route Targets are extended BGP communities that determine which VPN instances import and export those routes. Confusing these roles can lead to VPN connectivity problems, so understanding the separation between uniqueness and membership policy is fundamental.

Question 315.

In VRRP, what normally happens when the master router stops sending advertisements?

1. An eligible backup can take over the master role after the appropriate timeout
2. All hosts must immediately change their default gateway addresses
3. OSPF Area 0 is disabled
4. The virtual IP address is permanently removed

Correct Answer: 1. An eligible backup can take over the master role after the appropriate timeout

Explanation:

VRRP backup routers monitor advertisements from the master. If those advertisements stop and the master-down interval expires, an eligible backup can assume the master role and begin forwarding traffic for the virtual gateway. Hosts continue using the same virtual IP address, so the failover is transparent from their perspective. This is the fundamental mechanism through which VRRP protects default-gateway availability.

Question 316.

Which VRRP feature helps a network prefer a particular router after that router recovers?

1. MPLS PHP
2. Preemption
3. OSPF summarization
4. BGP route reflection

Correct Answer: 2. Preemption

Explanation:

VRRP preemption allows a router with a higher effective priority to reclaim the master role after it becomes operational again. This is useful when one gateway is deliberately designated as the preferred device during normal conditions. A preemption delay can be added so the recovering router has time to restore routing and upstream connectivity before taking over. This helps combine deterministic gateway preference with stable recovery behavior.

Question 317.

What is the primary purpose of configuring a maximum number of active links in an LACP aggregation?

1. Control how many member interfaces actively forward traffic in the bundle
2. Set the BGP AS number
3. Configure MPLS VPN membership
4. Select the OSPF backbone area

Correct Answer: 1. Control how many member interfaces actively forward traffic in the bundle

Explanation:

An LACP aggregation can have more candidate member links than are intended to forward simultaneously. Configuring the maximum number of active members allows some links to remain standby while a defined number carry traffic. If an active member fails, an eligible standby can be activated according to the aggregation rules. This can provide controlled redundancy and predictable link utilization in designs with multiple physical connections.

Question 318.

Which QoS mechanism determines whether traffic belongs to a voice, video, business-critical, or best-effort class?

1. Route reflection
2. Traffic classification
3. BFD
4. MPLS PHP

Correct Answer: 2. Traffic classification

Explanation:

Traffic classification examines selected packet characteristics and assigns traffic to defined QoS classes. Matching criteria can include addresses, protocols, ports, VLAN priorities, DSCP markings, or other supported fields. Once classified, packets can receive appropriate marking, policing, shaping, scheduling, or congestion-avoidance treatment. Classification is therefore the foundation of a QoS policy because later actions depend on correctly identifying the traffic that should receive each level of service.

Question 319.

What is the main purpose of a QoS trust boundary?

1. Define where incoming QoS markings are accepted, validated, or remarked according to policy
2. Determine the BGP Router ID
3. Select the VRRP master
4. Create an OSPF virtual link

Correct Answer: 1. Define where incoming QoS markings are accepted, validated, or remarked according to policy

Explanation:

A QoS trust boundary identifies where the network begins trusting or controlling packet markings such as DSCP. Traffic arriving from trusted devices may retain its markings, while traffic from untrusted sources can be reclassified or remarked. This prevents endpoints from assigning themselves inappropriate priority and helps maintain consistent QoS treatment across the network. Proper trust-boundary design is important for protecting high-priority queues from misuse.

Question 320.

Which design BEST supports predictable convergence and service continuity in a large Huawei routed network?

1. Use unrestricted route redistribution and identical metrics everywhere
2. Depend on one physical path for all critical services
3. Disable monitoring to reduce control-plane traffic
4. Use hierarchical routing, controlled policies, redundant paths, BFD where appropriate, gateway redundancy, and tested failover procedures**

Correct Answer: 4. Use hierarchical routing, controlled policies, redundant paths, BFD where appropriate, gateway redundancy, and tested failover procedures

Explanation:

Predictable network behavior depends on combining sound architecture with operational discipline. Hierarchical routing limits failure scope, while route policies prevent unintended information exchange. Redundant links and devices provide alternate paths, BFD can accelerate failure detection, and VRRP can protect the first-hop gateway. MPLS and QoS should also be designed with clear roles and consistent policies. Testing failure scenarios verifies that the network converges as expected instead of relying solely on theoretical redundancy.