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

 

Question 61.

What is the primary purpose of OSPF route summarization on an Area Border Router?

1. Reduce the number of inter-area routes advertised into other areas
2. Increase the number of LSAs throughout the network
3. Prevent all communication between OSPF areas
4. Convert OSPF routes into BGP routes automatically

Correct Answer: 1. Reduce the number of inter-area routes advertised into other areas

Explanation:

Route summarization on an OSPF ABR allows multiple related network prefixes to be represented by a broader summarized route when they are advertised between areas. This can reduce routing-table size, limit the amount of inter-area routing information, and decrease the impact of changes occurring inside one area. Effective summarization requires a well-structured IP addressing plan because unrelated prefixes cannot always be aggregated efficiently. Summarization improves scalability but should be designed carefully so that the resulting aggregate does not unintentionally attract traffic toward unreachable destinations.

Question 62.

Two OSPF routers remain in the ExStart state and do not reach Full. Which issue should be investigated?

1. BGP Local Preference
2. A possible MTU or database-exchange mismatch between the routers
3. MPLS Route Targets
4. STP root bridge priority

Correct Answer: 2. A possible MTU or database-exchange mismatch between the routers

Explanation:

The ExStart state occurs while OSPF neighbors negotiate how database synchronization will begin. If routers remain stuck in this state, administrators should investigate parameters that affect database exchange, including an interface MTU mismatch and related adjacency settings. Basic area, authentication, and timer parameters should also be verified during troubleshooting. BGP attributes, MPLS VPN membership, and spanning-tree priorities do not control the OSPF database synchronization process. Examining OSPF neighbor details and interface configuration is therefore the correct direction.

Question 63.

What is the main purpose of configuring an OSPF interface as passive?

1. Prevent the interface from forwarding IP packets
2. Remove the connected route from the routing table
3. Advertise the connected network without forming OSPF neighbor relationships on that interface
4. Disable OSPF entirely on the router

Correct Answer: 3. Advertise the connected network without forming OSPF neighbor relationships on that interface

Explanation:

A passive OSPF interface can still allow its connected network to be advertised through OSPF while suppressing OSPF Hello packets and neighbor formation on that interface. This is useful on user-facing or server-facing LANs where no OSPF router is expected. It reduces unnecessary protocol traffic and limits the possibility of unintended OSPF adjacencies. Passive-interface configuration does not disable normal IP forwarding on the interface and does not necessarily remove the connected prefix from OSPF advertisements.

Question 64.

In BGP, what does the Next_Hop attribute identify?

1. The OSPF router ID
2. The VLAN used by a route
3. The preferred spanning-tree path
4. The IP address that should be used as the next routing hop toward the advertised destination**

Correct Answer: 4. The IP address that should be used as the next routing hop toward the advertised destination

Explanation:

The BGP Next_Hop attribute identifies the next-hop IP address that a router should use to reach the destination represented by the BGP route. A BGP route generally cannot be installed as usable unless the next hop can be resolved through the local routing table. In iBGP designs, administrators sometimes modify next-hop behavior so internal routers can reach the appropriate gateway. Troubleshooting BGP therefore frequently includes checking whether the advertised next hop is reachable through an IGP, static route, or directly connected network.

Question 65.

Why is BGP Next_Hop reachability important?

1. A BGP route normally requires a reachable next hop before it can be used for forwarding
2. It determines the STP root bridge
3. It assigns an MPLS Route Distinguisher
4. It selects the DHCP address pool

Correct Answer: 1. A BGP route normally requires a reachable next hop before it can be used for forwarding

Explanation:

BGP can learn a route from a peer even when the route’s Next_Hop address is not currently reachable. However, the router must be able to resolve that next-hop address before the route can normally become usable for packet forwarding. In many designs, an IGP such as OSPF or IS-IS provides reachability to internal BGP next hops. If a valid BGP route is not becoming active, checking next-hop reachability is therefore an important troubleshooting step before changing BGP policy or attributes.

Question 66.

What is the main purpose of a BGP peer group?

1. Replace the BGP AS number
2. Simplify configuration by applying common peer settings to multiple BGP neighbors
3. Create an MPLS forwarding label
4. Elect the OSPF DR

Correct Answer: 2. Simplify configuration by applying common peer settings to multiple BGP neighbors

Explanation:

A BGP peer group allows several neighbors with similar requirements to share common configuration. Policies, timers, address-family settings, or other parameters can be associated with the group rather than configured independently for every peer. This reduces repetitive configuration and can make large BGP deployments easier to maintain consistently. Individual neighbors may still require specific settings depending on the implementation. Peer groups are a management and scalability feature rather than a replacement for autonomous system numbers or routing-policy design.

Question 67.

What is the purpose of applying a routing policy when redistributing routes between OSPF and BGP?

1. Automatically encrypt the redistributed routes
2. Create Ethernet VLANs
3. Control which routes are redistributed and how their attributes or metrics are modified
4. Disable loop prevention

Correct Answer: 3. Control which routes are redistributed and how their attributes or metrics are modified

Explanation:

Route redistribution should rarely be performed without policy control. A routing policy can match specific prefixes, route tags, or other attributes and then permit, deny, or modify routes as they cross protocol boundaries. This helps prevent unnecessary route propagation and reduces the risk of routing loops. Administrators can also adjust metrics or BGP attributes during redistribution. Uncontrolled redistribution between protocols can create complex feedback paths, so clear filtering and tagging strategies are important in enterprise and service-provider networks.

Question 68.

What is the main purpose of route tagging during redistribution?

1. Encrypt route advertisements
2. Increase interface bandwidth
3. Replace prefix filtering
4. Mark redistributed routes so policies can identify their origin and prevent undesirable redistribution loops**

Correct Answer: 4. Mark redistributed routes so policies can identify their origin and prevent undesirable redistribution loops

Explanation:

Route tags provide metadata that routing policies can use to identify where a redistributed route originated. For example, routes moved from one protocol into another can be tagged so they are not later redistributed back into the original protocol. This helps prevent routing feedback and loops in networks using multiple routing domains. Tags do not directly encrypt routes or increase link capacity. They are most effective when incorporated into a clear redistribution policy with prefix filtering and metric control.

Question 69.

In IPv6, what is the purpose of a link-local address?

1. Support communication on the local link and functions such as neighbor discovery
2. Provide globally routable internet connectivity by itself
3. Replace all multicast addresses
4. Identify an MPLS VPN

Correct Answer: 1. Support communication on the local link and functions such as neighbor discovery

Explanation:

IPv6 link-local addresses are automatically associated with interfaces and are used for communication within the local Layer 2 segment. They play an important role in IPv6 Neighbor Discovery, router discovery, and many routing-protocol operations. Link-local addresses are not normally routed beyond the local link, so they do not replace global unicast addresses for end-to-end connectivity. Their scope makes them useful for local protocol communication without requiring globally unique addressing on every control-plane exchange.

Question 70.

Which IPv6 mechanism performs functions similar to IPv4 ARP?

1. VRRP
2. Neighbor Discovery
3. MPLS LDP
4. BGP Route Reflection

Correct Answer: 2. Neighbor Discovery

Explanation:

IPv6 Neighbor Discovery uses ICMPv6 messages to perform several functions, including resolving neighboring IPv6 addresses to link-layer addresses, discovering routers, learning network prefixes, and detecting certain reachability changes. It replaces the role that ARP performs for IPv4 address-to-MAC resolution while also supporting additional IPv6 functions. Neighbor Discovery is fundamental to normal IPv6 operation. VRRP, LDP, and route reflection serve redundancy, MPLS signaling, and BGP scaling functions respectively.

Question 71.

What is the primary purpose of IPv6 Router Advertisement messages?

1. Distribute BGP attributes
2. Elect the OSPF DR
3. Inform IPv6 hosts about routers, prefixes, and address-configuration information
4. Build MPLS labels

Correct Answer: 3. Inform IPv6 hosts about routers, prefixes, and address-configuration information

Explanation:

IPv6 routers send Router Advertisements as part of Neighbor Discovery. These messages can tell hosts that a router is available as a default gateway and can advertise IPv6 prefixes and configuration flags. Depending on the network design, hosts may use this information for stateless address autoconfiguration or in combination with DHCPv6. Router Advertisements therefore play an important role in IPv6 host configuration and default-router discovery. They are unrelated to BGP attributes or MPLS label distribution.

Question 72.

What is the purpose of DHCPv6 in an IPv6 network?

1. Prevent Layer 2 loops
2. Create BGP peerings
3. Replace all IPv6 routing protocols
4. Provide IPv6 configuration information to clients, depending on the deployment mode**

Correct Answer: 4. Provide IPv6 configuration information to clients, depending on the deployment mode

Explanation:

DHCPv6 can provide IPv6 hosts with configuration information such as addresses, DNS server details, and other parameters depending on whether stateful or complementary operation is used. IPv6 networks may combine DHCPv6 with Router Advertisements because the two mechanisms perform related but distinct roles. The exact design depends on how administrators want clients to obtain addressing and additional configuration. DHCPv6 does not perform Layer 2 loop prevention or replace dynamic routing protocols.

Question 73.

What is the primary function of PIM in an IP multicast network?

1. Build multicast distribution paths between routers
2. Assign unicast IP addresses to hosts
3. Encrypt multicast packets
4. Create BGP communities

Correct Answer: 1. Build multicast distribution paths between routers

Explanation:

Protocol Independent Multicast, or PIM, is used by routers to construct multicast forwarding trees across an IP network. It is called protocol independent because it relies on the existing unicast routing table for reachability information rather than maintaining a separate unicast topology database. Different PIM modes are appropriate for different multicast distribution patterns. PIM handles router-to-router multicast forwarding, while host membership protocols such as IGMP are used between IPv4 hosts and their local multicast router.

Question 74.

What is the main function of IGMP in an IPv4 multicast environment?

1. Exchange BGP routes
2. Allow hosts to report multicast group membership to local routers
3. Distribute MPLS labels
4. Provide gateway redundancy

Correct Answer: 2. Allow hosts to report multicast group membership to local routers

Explanation:

Internet Group Management Protocol allows IPv4 hosts to indicate which multicast groups they want to receive. The local multicast router uses this information to determine whether multicast traffic for a group is needed on that subnet. IGMP operates between hosts and their local multicast routers, while PIM is generally used among routers to construct multicast distribution paths through the network. IGMP therefore provides multicast receiver membership signaling rather than unicast routing or first-hop gateway redundancy.

Question 75.

What is the purpose of an RP in PIM Sparse Mode?

1. Assign VLAN IDs
2. Select OSPF costs
3. Provide a common rendezvous point used during multicast source and receiver discovery
4. Replace multicast routing entirely

Correct Answer: 3. Provide a common rendezvous point used during multicast source and receiver discovery

Explanation:

PIM Sparse Mode uses a Rendezvous Point as a logical meeting location for multicast sources and receivers, especially during initial tree formation. Receivers can join toward the RP, while source information is registered so multicast traffic can begin flowing. Depending on traffic and implementation, routers may later transition to a shortest-path tree directly toward the source. RP placement and redundancy should be planned carefully because the RP has an important control-plane role in sparse-mode multicast operation.

Question 76.

What is the main difference between traffic policing and traffic shaping?

1. Policing always uses more bandwidth than shaping
2. Shaping works only for multicast
3. Policing is a routing protocol
4. Shaping can buffer excess traffic, while policing commonly drops or remarks traffic that exceeds a rate**

Correct Answer: 4. Shaping can buffer excess traffic, while policing commonly drops or remarks traffic that exceeds a rate

Explanation:

Traffic shaping attempts to smooth traffic toward a configured rate by buffering packets during bursts and transmitting them later. This can reduce packet loss but may introduce additional delay. Traffic policing generally enforces a rate without relying on large buffering; traffic exceeding the permitted profile may be dropped or remarked. The choice between shaping and policing depends on whether excess traffic should be delayed or immediately constrained. Both are QoS mechanisms rather than routing protocols.

Question 77.

What is the purpose of marking packets with DSCP values?

1. Indicate a traffic class so network devices can apply differentiated QoS treatment
2. Assign an MPLS VPN Route Distinguisher
3. Elect an STP root bridge
4. Create an OSPF neighbor relationship

Correct Answer: 1. Indicate a traffic class so network devices can apply differentiated QoS treatment

Explanation:

DSCP values are carried in the IP header and can be used to classify or mark traffic according to its service requirements. Network devices can then apply different queueing, policing, shaping, or drop behavior based on the traffic class. For example, delay-sensitive voice traffic may receive different treatment from bulk data transfers. DSCP markings are useful only when the network applies a consistent QoS policy and defines appropriate trust boundaries. They do not perform routing-protocol or Layer 2 control functions.

Question 78.

A network administrator wants voice traffic to be transmitted ahead of ordinary data during congestion. Which QoS function is MOST relevant?

1. Route redistribution
2. Priority queueing or an equivalent scheduling mechanism
3. OSPF summarization
4. BGP route reflection

Correct Answer: 2. Priority queueing or an equivalent scheduling mechanism

Explanation:

Queue scheduling determines how packets waiting on a congested interface are selected for transmission. A priority mechanism can provide delay-sensitive traffic such as voice with preferential service compared with lower-priority data. Administrators must configure priority bandwidth carefully so one class does not starve other traffic. Classification and marking are also important because the device must first identify which packets belong to the priority class. Routing features such as summarization or route reflection do not directly control congestion queue service.

Question 79.

What is a major benefit of using BFD with a dynamic routing protocol?

1. BFD replaces the routing protocol completely
2. BFD assigns IP addresses dynamically
3. BFD can detect forwarding-path failures rapidly and trigger faster routing convergence
4. BFD encrypts all routing traffic

Correct Answer: 3. BFD can detect forwarding-path failures rapidly and trigger faster routing convergence

Explanation:

Dynamic routing protocols typically have their own Hello or keepalive mechanisms, but their default failure-detection intervals may be longer than required by delay-sensitive networks. BFD provides a lightweight mechanism for rapidly detecting whether a forwarding path between two devices has failed. The routing protocol can then react to that failure and calculate an alternate route sooner. BFD does not replace OSPF, IS-IS, or BGP because it does not exchange reachability information or calculate routes itself.

Question 80.

Which design BEST supports reliable operation in a network using IPv4, IPv6, dynamic routing, multicast, and QoS?

1. Use one flat Layer 2 domain and avoid routing hierarchy
2. Disable redundancy to simplify troubleshooting
3. Use uncontrolled redistribution between every routing protocol
4. Apply hierarchical addressing, controlled routing policy, redundancy, monitoring, multicast design, and consistent QoS classification**

Correct Answer: 4. Apply hierarchical addressing, controlled routing policy, redundancy, monitoring, multicast design, and consistent QoS classification

Explanation:

Complex networks are easier to scale when each technology is incorporated into a structured architecture. Hierarchical addressing supports summarization, controlled route policies prevent unintended propagation, and redundant paths improve availability. IPv4 and IPv6 should be planned consistently rather than treated as unrelated overlays. Multicast requires deliberate receiver, routing, and RP design, while QoS requires consistent classification, marking, and queue treatment. Fast failure detection and monitoring further improve resilience. Combining these practices produces a more predictable network than relying on flat topology or uncontrolled protocol interaction.