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

 

Question 1.

In an OSPF network, what is the primary function of the designated router (DR) on a broadcast network?

1. Reduce the number of OSPF adjacencies and LSA exchanges
2. Assign IP addresses to OSPF routers
3. Select the default gateway for all hosts
4. Redistribute BGP routes automatically

Correct Answer: 1. Reduce the number of OSPF adjacencies and LSA exchanges

Explanation:

On a broadcast multi-access network, forming a full adjacency between every pair of OSPF routers would create unnecessary protocol overhead. OSPF therefore elects a designated router and backup designated router. Other routers primarily establish full adjacencies with the DR and BDR rather than with every router on the segment. The DR helps coordinate LSA exchange on the shared network, reducing the total number of adjacencies and improving scalability. DR election is based on interface priority and router ID, but the DR does not assign addresses or automatically redistribute routes.

Question 2.

Which OSPF router type has at least one interface in Area 0 and at least one interface in another OSPF area?

1. Internal router
2. Area Border Router
3. Autonomous System Boundary Router
4. Designated Router

Correct Answer: 2. Area Border Router

Explanation:

An Area Border Router, or ABR, connects the OSPF backbone area, Area 0, to one or more non-backbone areas. It maintains separate link-state databases for the areas to which it belongs and can advertise summary information between areas. An internal router has all OSPF interfaces in the same area. An ASBR introduces routes from another routing domain or protocol into OSPF. A DR is elected on certain multi-access network segments and performs a different function from an ABR.

Question 3.

Which BGP attribute is commonly used inside an autonomous system to indicate a preferred exit point, with a higher value being preferred?

1. MED
2. Origin
3. Local Preference
4. AS_Path

Correct Answer: 3. Local Preference

Explanation:

Local Preference is a well-known discretionary BGP attribute used within an autonomous system to influence outbound traffic. When multiple BGP routes to the same destination exist, a route with a higher Local Preference is generally preferred before several later BGP path-selection criteria are considered. MED usually influences how external neighbors choose an entry point into an autonomous system, with lower values normally preferred. AS_Path records the autonomous systems a route has traversed and is also important for loop prevention.

Question 4.

What is the main purpose of the BGP AS_Path attribute?

1. Identify the VLAN carrying the route
2. Select the OSPF DR
3. Encrypt BGP updates
4. Record traversed autonomous systems and help prevent routing loops**

Correct Answer: 4. Record traversed autonomous systems and help prevent routing loops

Explanation:

The AS_Path attribute contains the sequence of autonomous system numbers through which a BGP route has passed. When a BGP router receives a route containing its own AS number in the AS_Path, it normally rejects that route, which provides an important loop-prevention mechanism. AS_Path length is also used during BGP route selection, with shorter paths generally preferred when earlier selection criteria are equal. The attribute does not carry VLAN information, perform encryption, or participate in OSPF DR election.

Question 5.

What is the primary purpose of route summarization in a large routing domain?

1. Reduce routing table size and limit the impact of topology changes
2. Increase the number of advertised prefixes
3. Disable route convergence
4. Force every router to maintain all detailed routes**

Correct Answer: 1. Reduce routing table size and limit the impact of topology changes

Explanation:

Route summarization combines multiple specific prefixes into a broader aggregate route where the address plan permits it. This can reduce the number of routing entries distributed through the network and decrease the amount of routing information that must be processed. Summarization can also contain the effect of certain topology changes because instability in a specific subnet does not always need to be propagated outside the summarized region. A carefully designed hierarchical address plan makes summarization more effective and helps improve routing scalability.

Question 6.

In an IS-IS network, what is the primary role of a Level-1 router?

1. Exchange only external BGP routes
2. Maintain detailed routing information within its Level-1 area
3. Operate exclusively as an MPLS provider edge router
4. Elect the OSPF DR

Correct Answer: 2. Maintain detailed routing information within its Level-1 area

Explanation:

An IS-IS Level-1 router maintains detailed topology information for its own area. For destinations outside the area, it normally relies on a Level-1-2 router to provide connectivity toward other areas. Level-2 routing provides inter-area connectivity within the IS-IS domain, while Level-1-2 routers participate in both levels. This hierarchical design limits the amount of topology information that every router must maintain. IS-IS operation is separate from OSPF DR election and does not inherently require MPLS.

Question 7.

Which device type in IS-IS can exchange routing information with both Level-1 and Level-2 routers?

1. Level-0 router
2. Stub router only
3. Level-1-2 router
4. BGP route reflector

Correct Answer: 3. Level-1-2 router

Explanation:

A Level-1-2 router participates in both Level-1 and Level-2 IS-IS routing. It can maintain intra-area Level-1 information while also participating in the Level-2 backbone used for communication between areas. Level-1 routers can use Level-1-2 routers as exits toward destinations outside their own areas. This enables hierarchical routing and improves scalability. A BGP route reflector serves an entirely different purpose inside iBGP and is not an IS-IS router level.

Question 8.

What is the main purpose of VRRP in an enterprise network?

1. Encrypt routing updates
2. Replace VLAN tagging
3. Provide BGP route reflection
4. Provide default-gateway redundancy for hosts**

Correct Answer: 4. Provide default-gateway redundancy for hosts

Explanation:

VRRP allows multiple routers or Layer 3 switches to present a shared virtual gateway address to hosts. One device operates as the master and forwards traffic for the virtual IP address, while another device can take over if the master becomes unavailable. Hosts continue using the same configured default gateway, reducing disruption during a gateway failure. VRRP therefore improves first-hop availability. It does not replace VLANs, encrypt routing information, or provide BGP route-reflector functionality.

Question 9.

What is the purpose of an Eth-Trunk on Huawei network devices?

1. Combine multiple physical Ethernet links into one logical link
2. Replace all Layer 3 routing protocols
3. Assign wireless channels
4. Translate private addresses into public addresses

Correct Answer: 1. Combine multiple physical Ethernet links into one logical link

Explanation:

An Eth-Trunk aggregates multiple physical Ethernet interfaces into a single logical interface. This can increase available bandwidth and provide link redundancy. If one member link fails, traffic can continue over the remaining active links, depending on the configuration. Load distribution is normally based on selected traffic characteristics rather than splitting every individual packet evenly. Eth-Trunk technology is commonly used between switches, routers, and servers where additional capacity and resilience are required.

Question 10.

What is the main advantage of using LACP with an Eth-Trunk?

1. It automatically creates OSPF areas
2. It provides negotiation and monitoring of link aggregation members
3. It replaces STP across the network
4. It assigns IP addresses to hosts

Correct Answer: 2. It provides negotiation and monitoring of link aggregation members

Explanation:

LACP provides a standardized mechanism for negotiating and managing link aggregation. Devices exchange LACP information to determine which interfaces can participate in the same logical link and which members should actively forward traffic. This makes link aggregation easier to manage and can help detect incompatible or failed member links. Static aggregation can operate without LACP, but it lacks the same negotiation capability. LACP does not create routing areas, provide DHCP, or completely replace spanning-tree functions.

Question 11.

What problem is the Spanning Tree Protocol designed to prevent in a switched Ethernet network?

1. BGP route loops
2. DHCP address exhaustion
3. Layer 2 forwarding loops
4. OSPF adjacency formation

Correct Answer: 3. Layer 2 forwarding loops

Explanation:

Redundant Ethernet links improve availability but can create Layer 2 loops. Because Ethernet frames do not contain a routing-style hop limit, loops can cause broadcast storms, duplicate frames, and instability in MAC address tables. Spanning Tree Protocol creates a loop-free logical topology by placing selected redundant paths into a non-forwarding state. If an active link fails, a previously blocked path can become active. STP therefore provides Layer 2 redundancy while preventing forwarding loops.

Question 12.

What is a key benefit of MSTP compared with running a separate spanning-tree instance for every VLAN?

1. It eliminates the need for VLANs
2. It converts Layer 2 traffic into BGP
3. It disables redundant links permanently
4. Multiple VLANs can be mapped to the same spanning-tree instance**

Correct Answer: 4. Multiple VLANs can be mapped to the same spanning-tree instance

Explanation:

Multiple Spanning Tree Protocol improves scalability by allowing multiple VLANs to share a spanning-tree instance. Instead of maintaining a completely independent spanning tree for each VLAN, administrators can group VLANs with similar topology requirements into the same MST instance. Different instances can use different forwarding paths, which can also provide traffic-engineering benefits. MSTP retains loop-prevention functionality while reducing control-plane overhead compared with maintaining a very large number of independent spanning-tree instances.

Question 13.

What is the primary purpose of DHCP relay?

1. Forward DHCP messages between clients and a DHCP server located on another subnet
2. Convert IPv4 traffic to IPv6
3. Establish BGP neighbor relationships
4. Encrypt DHCP packets

Correct Answer: 1. Forward DHCP messages between clients and a DHCP server located on another subnet

Explanation:

Initial DHCP client messages are normally broadcast and do not cross routers. A DHCP relay agent receives those client messages and forwards them to a DHCP server on another IP subnet. The relay also provides information that helps the server determine which address pool should be used for the client. This allows an organization to centralize DHCP services rather than deploying a server on every subnet. DHCP relay does not perform routing-protocol functions or provide packet encryption.

Question 14.

Which QoS process places traffic into different classes based on fields such as addresses, protocols, or application characteristics?

1. Fragmentation
2. Traffic classification
3. Route summarization
4. Spanning-tree election

Correct Answer: 2. Traffic classification

Explanation:

Traffic classification identifies packets or flows and assigns them to traffic classes based on configured criteria. Those criteria can include source or destination addresses, protocol values, ports, DSCP markings, or other characteristics. Once traffic has been classified, QoS mechanisms can apply different treatment such as marking, policing, shaping, or queue scheduling. Classification is therefore an early and important step in implementing differentiated service. It does not itself determine routing topology or spanning-tree behavior.

Question 15.

A network administrator wants to enforce a maximum traffic rate and immediately drop or remark traffic that exceeds the configured limit. Which QoS mechanism is most appropriate?

1. Route aggregation
2. VRRP
3. Traffic policing
4. LACP

Correct Answer: 3. Traffic policing

Explanation:

Traffic policing measures traffic against a configured rate profile and can take immediate action on traffic that exceeds the permitted rate. Depending on policy, excess packets may be dropped or remarked. Policing does not normally buffer large quantities of excess traffic for later transmission. Traffic shaping, by contrast, generally uses buffering to smooth traffic toward a target rate. Policing is therefore useful when an organization needs to enforce bandwidth limits and prevent a traffic class from consuming more capacity than allowed.

Question 16.

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

1. Shaping is used only for routing protocols
2. Policing always increases bandwidth
3. Shaping disables congestion management
4. Shaping can buffer excess traffic, whereas policing commonly drops or remarks excess traffic**

Correct Answer: 4. Shaping can buffer excess traffic, whereas policing commonly drops or remarks excess traffic

Explanation:

Traffic shaping attempts to smooth traffic by temporarily buffering packets that exceed the configured transmission rate and sending them later when capacity becomes available. This can reduce burstiness but introduces delay and requires buffer resources. Traffic policing generally measures traffic against a rate and acts immediately on traffic that exceeds the limit, commonly by dropping or remarking packets. The appropriate mechanism depends on whether the network should delay excess traffic or enforce a hard rate without significant buffering.

Question 17.

In MPLS, what information does a label primarily provide to an MPLS-capable forwarding device?

1. A forwarding identifier used to select the next label-switched action
2. A Wi-Fi encryption key
3. The OSPF area password
4. The Ethernet VLAN database

Correct Answer: 1. A forwarding identifier used to select the next label-switched action

Explanation:

MPLS attaches a label to packets so label-switching routers can make forwarding decisions using label information. A router receiving a labeled packet examines the incoming label and determines the appropriate forwarding action, such as swapping it for another label, removing it, or forwarding it toward the next hop. This creates label-switched paths through an MPLS domain. MPLS labels are forwarding identifiers and are not encryption keys, VLAN databases, or routing-protocol authentication information.

Question 18.

What is a major purpose of MPLS Layer 3 VPN technology?

1. Replace all customer IP addressing
2. Provide logically isolated customer routing domains across a shared provider network
3. Eliminate the need for routing tables
4. Disable BGP in the provider network

Correct Answer: 2. Provide logically isolated customer routing domains across a shared provider network

Explanation:

MPLS Layer 3 VPNs allow a service provider to transport routing information for multiple customers across a shared backbone while maintaining logical separation between customer routing domains. Provider edge devices use mechanisms such as separate VPN routing and forwarding instances to keep customer routes distinct. MP-BGP can distribute VPN route information between provider edge routers. Customers can therefore use overlapping address spaces without those routes being mixed directly. The design improves scalability compared with building a completely separate physical provider network for every customer.

Question 19.

What is the main function of a BGP route reflector in a large iBGP network?

1. Encrypt BGP updates
2. Provide DHCP relay
3. Reduce the requirement for a full mesh of iBGP peerings
4. Elect the spanning-tree root bridge

Correct Answer: 3. Reduce the requirement for a full mesh of iBGP peerings

Explanation:

Traditional iBGP design requires routers within the same autonomous system to maintain a full mesh because routes learned from one iBGP neighbor are not normally advertised to another iBGP neighbor. This becomes difficult to scale as the number of routers grows. A route reflector relaxes that requirement by reflecting selected iBGP routes between its clients. This significantly reduces the number of BGP peerings needed. Route-reflector design should still provide adequate redundancy and avoid undesirable routing behavior.

Question 20.

Which approach BEST supports a scalable and resilient enterprise routing design?

1. Use one large Layer 2 broadcast domain for every user
2. Disable redundant links
3. Advertise every route without considering hierarchy or summarization
4. Use hierarchical design, route summarization, redundant paths, and appropriate dynamic routing protocols**

Correct Answer: 4. Use hierarchical design, route summarization, redundant paths, and appropriate dynamic routing protocols

Explanation:

A scalable enterprise network normally combines hierarchy, structured addressing, route summarization, dynamic routing, and redundant connectivity. Hierarchy limits failure domains and simplifies troubleshooting, while summarization reduces routing-table size and the propagation of detailed topology changes. Redundant paths improve availability, and protocols such as OSPF, IS-IS, or BGP can provide automated route convergence according to the design requirements. Large uncontrolled Layer 2 domains and unnecessary routing detail generally increase complexity rather than improve scalability.