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Question 361. What is the PRIMARY purpose of an IP prefix list on a Huawei router?

1. To encrypt routing updates
2. To match routes according to destination prefixes and prefix lengths for routing-policy control
3. To assign VLAN IDs
4. To create BGP TCP sessions

Correct Answer: 2. To match routes according to destination prefixes and prefix lengths for routing-policy control

Explanation:

An IP prefix list is designed specifically for route matching. It can identify routes according to their network prefix and mask length and can also match a range of prefix lengths using options such as greater-equal and less-equal. This makes prefix lists particularly suitable for routing policies, route filtering, redistribution control, and BGP import or export filtering. Unlike packet ACLs, which are frequently used to classify traffic, prefix lists focus directly on routing prefixes. Huawei processes prefix-list entries according to their indexes and stops after a route matches an applicable entry.

Question 362. In an IPv4 prefix list, what does the less-equal parameter specify?

1. The minimum allowed route preference
2. The smallest permitted AS number
3. The lowest allowed prefix length
4. The maximum prefix length that can match the prefix-list entry

Correct Answer: 4. The maximum prefix length that can match the prefix-list entry

Explanation:

The Huawei less-equal option defines the upper boundary of the matching mask-length range in an IP prefix list. For example, a rule based on 10.0.0.0/8 with less-equal 24 can match qualifying more-specific routes whose prefix lengths fall between the base mask length and /24. If both greater-equal and less-equal are specified, they define the minimum and maximum accepted prefix lengths respectively. Huawei requires the configured values to satisfy the logical relationship between the base mask, lower threshold, upper threshold, and the IPv4 maximum of /32.

Question 363. What does the greater-equal parameter in a Huawei IP prefix list control?

1. The minimum prefix length that a matching route must have
2. The maximum BGP MED value
3. The largest Local Preference value
4. The minimum route preference

Correct Answer: 1. The minimum prefix length that a matching route must have

Explanation:

The greater-equal parameter specifies the minimum prefix length that a matching route must have. For example, if a prefix-list entry is based on 10.0.0.0/8 and includes greater-equal 17, routes must have a prefix length of at least /17 while still falling within the configured base prefix. If less-equal is also configured, the two parameters define a bounded range. Prefix-length filtering is useful when an administrator wants to accept or reject only certain more-specific routes rather than matching one exact subnet mask.

Question 364. What happens if a route matches none of the entries in a Huawei IP prefix list used directly for route filtering?

1. The route is automatically converted to a default route
2. The route is always permitted
3. The route is rejected by default
4. The route is installed with preference 255

Correct Answer: 3. The route is rejected by default

Explanation:

Huawei prefix lists use an implicit rejection behavior for routes that fail to match any permitted entry. This is why a prefix list containing only deny entries can unintentionally block every route. If the administrator wants to reject selected prefixes but permit everything else, a final broad permit entry is commonly added, such as one matching 0.0.0.0/0 with less-equal 32. This behavior is important when troubleshooting route-policy or filter-policy configurations because an omitted catch-all permit statement can cause more routes to disappear than originally intended.

Question 365. What is the effect of the following prefix-list entry: ip ip-prefix TEST permit 10.0.0.0 8 greater-equal 16 less-equal 24?

1. It permits qualifying routes within 10.0.0.0/8 whose prefix lengths range from /16 through /24
2. It permits only 10.0.0.0/8 exactly
3. It permits all IPv4 routes
4. It permits only routes longer than /24

Correct Answer: 1. It permits qualifying routes within 10.0.0.0/8 whose prefix lengths range from /16 through /24

Explanation:

The base network in this prefix list is 10.0.0.0/8. The greater-equal 16 statement requires a matching route to have a mask length of at least /16, while less-equal 24 limits the maximum length to /24. Therefore, qualifying routes must belong to the 10.0.0.0/8 address space and have prefix lengths from /16 through /24 inclusive. Prefix lists provide this type of precise route control more naturally than ordinary traffic ACLs because both the network prefix and route-mask range can be evaluated directly.

Question 366. What is the PRIMARY purpose of an AS_Path filter in Huawei BGP policy control?

1. To match VLAN tags
2. To modify OSPF cost directly
3. To allocate MPLS labels
4. To match BGP routes according to the autonomous system numbers contained in their AS_Path attributes

Correct Answer: 4. To match BGP routes according to the autonomous system numbers contained in their AS_Path attributes

Explanation:

An AS_Path filter allows Huawei devices to classify BGP routes according to patterns found in the AS_Path attribute. Because AS_Path records the sequence of autonomous systems a route has traversed, administrators can use regular expressions to identify routes originating from, passing through, or matching particular AS combinations. The filter can then be referenced by a route-policy using if-match as-path-filter. This provides powerful control over BGP import and export policy without matching individual IP prefixes. Huawei supports numbered or named AS_Path filters containing permit and deny expressions.

Question 367. What does a Huawei community filter primarily match?

1. Interface bandwidth values
2. BGP community attributes attached to routes
3. MPLS transport labels
4. OSPF router priorities

Correct Answer: 2. BGP community attributes attached to routes

Explanation:

BGP communities are tags attached to routes so routing policy can treat groups of routes consistently. A Huawei community filter is designed to match routes according to those community attributes. Rather than maintaining a separate prefix list for every route, an operator can tag related prefixes with a common value and then apply import, export, or attribute-modification policy based on the tag. This provides scalable routing policy, especially in service-provider and large enterprise environments. Well-known communities such as No_Export can also affect how far routes may be propagated beyond the current autonomous system.

Question 368. In a Huawei route-policy, what is the role of an if-match clause?

1. It immediately modifies BGP attributes
2. It installs the route in the forwarding table
3. It defines the conditions a route must satisfy for that route-policy node to match
4. It automatically creates a new routing protocol

Correct Answer: 3. It defines the conditions a route must satisfy for that route-policy node to match

Explanation:

A route-policy is built from nodes that contain matching conditions and optional actions. The if-match clauses define those conditions. They can reference information such as IP prefix lists, ACLs, AS_Path filters, communities, route tags, or route preferences depending on the platform and protocol. When a route satisfies the matching logic of a permit node, the route can be accepted and any configured apply actions can modify its attributes. This separation between matching and action makes route-policy highly flexible for import, export, redistribution, and BGP traffic-engineering scenarios.

Question 369. What is the PRIMARY function of an apply clause in a Huawei route-policy?

1. To specify packet encryption
2. To elect a BGP route reflector
3. To define the route-policy node number
4. To modify route attributes or parameters after the route matches the policy node

Correct Answer: 4. To modify route attributes or parameters after the route matches the policy node

Explanation:

After a route satisfies the matching conditions in a route-policy node, apply clauses can change relevant route attributes. Depending on the protocol and platform, these actions may modify attributes such as cost, tag, preference, Local Preference, MED, communities, or other supported properties. Huawei’s route-policy output explicitly distinguishes Match clauses from Apply clauses. This makes the logic straightforward: if-match identifies the routes of interest, while apply determines how matching routes should be modified. Route-policy can therefore provide both filtering and attribute-manipulation functions.

Question 370. Why are route-policy node sequence numbers important?

1. They determine the device’s router ID
2. Route-policy nodes are evaluated according to their sequence, so a route may match an earlier node before later nodes are considered
3. They define the BGP TCP port
4. They identify the VLAN used by the policy

Correct Answer: 2. Route-policy nodes are evaluated according to their sequence, so a route may match an earlier node before later nodes are considered

Explanation:

A route-policy can contain several numbered nodes, allowing specific route conditions to be evaluated before broader ones. Proper ordering is therefore important. An early node might deny a selected prefix, while a later node permits and modifies a broader set of routes. If the rules are placed in the wrong sequence, a broad earlier condition can prevent a more specific later policy from ever taking effect. Administrators commonly leave gaps between node numbers so additional logic can be inserted later without renumbering the entire policy. This structured sequencing makes route-policy easier to expand and maintain.

Question 371. Which Huawei command family is commonly used to filter routes entering or leaving a routing protocol process without necessarily modifying route attributes?

1. filter-policy
2. traffic-filter
3. port-security
4. mac-address

Correct Answer: 1. filter-policy

Explanation:

Huawei routing protocols commonly support the filter-policy mechanism to control which routes are imported, installed, or advertised depending on the protocol and configuration context. A filter-policy can reference an IP prefix list, ACL, or other supported filtering tool. For example, Huawei OSPF troubleshooting documentation shows filter-policy ip-prefix import being used to prevent selected OSPF routes from entering the local routing table. This differs from interface traffic-filter, which applies packet filtering to data-plane traffic. Route filtering therefore operates on routing information rather than ordinary user packets.

Question 372. If OSPF has learned a route into its OSPF routing information but filter-policy import denies that route, what is the expected local effect?

1. The LSA is necessarily removed from every router’s LSDB
2. The route is automatically redistributed into BGP
3. The route can be prevented from being installed in the local IP routing table even though OSPF may still know the route
4. The entire OSPF adjacency is torn down

Correct Answer: 3. The route can be prevented from being installed in the local IP routing table even though OSPF may still know the route

Explanation:

Huawei distinguishes between OSPF’s protocol information and the device’s final local routing table. An OSPF filter-policy import can filter routes when they are being added to the local routing table. Huawei documentation notes that the device may still maintain the corresponding OSPF routing or LSA information even though the filtered route does not become an active local IP route. This is an important troubleshooting distinction: filtering a learned route locally does not necessarily mean the OSPF LSA disappeared from the LSDB or that neighbors stopped advertising it.

Question 373. What is the PRIMARY purpose of applying an export policy to BGP?

1. To control which routes and attributes are advertised from the local BGP router to selected peers
2. To control which Ethernet frames enter a switch port
3. To select the VRRP Master
4. To assign DHCP options

Correct Answer: 2. To control which routes and attributes are advertised from the local BGP router to selected peers

Explanation:

A BGP export policy controls information leaving the local BGP speaker. It can determine which routes are advertised to a particular peer and can modify BGP attributes before advertisement. This is essential for implementing routing contracts, controlling Internet announcements, preventing accidental route leaks, and performing traffic engineering. Huawei BGP processing supports routing policies both when routes are imported into BGP and when routes are received from or advertised to peers. Export policy should therefore be designed carefully because an incorrect permit rule can advertise unintended internal or customer prefixes.

Question 374. What is the PRIMARY purpose of a BGP import policy applied to a peer?

1. To change STP port roles
2. To configure DHCP relay
3. To set MPLS tunnel bandwidth
4. To control which received BGP routes are accepted and optionally modify their attributes

Correct Answer: 4. To control which received BGP routes are accepted and optionally modify their attributes

Explanation:

A BGP import policy is applied to routes received from a peer before those routes are accepted into the local BGP decision process. The policy can reject unwanted prefixes or match selected routes and alter attributes such as Local Preference or other supported values. This is useful for protecting the network against unwanted advertisements and for influencing which external or internal paths the local autonomous system prefers. Huawei BGP supports routing-policy application during route import, peer reception, and route export, allowing control at multiple stages of route processing.

Question 375. What is a major reason to filter redistributed routes between two routing protocols?

1. To reduce the risk of unintended route propagation or routing loops between the two domains
2. To increase every route’s metric automatically
3. To disable all route selection
4. To ensure every route is redistributed in both directions

Correct Answer: 1. To reduce the risk of unintended route propagation or routing loops between the two domains

Explanation:

Mutual redistribution can create serious problems if routes learned from one protocol are injected into another and later redistributed back toward their original source. Filtering and route tagging help administrators control exactly which routes cross protocol boundaries and prevent routes from circulating between routing domains. Good redistribution design therefore uses explicit policies rather than indiscriminately importing every available route. Administrators may match prefixes, tags, protocol source, or other attributes and then permit only the routes that have a genuine business or topology requirement to cross the boundary.

Question 376. Why are route tags useful during mutual redistribution?

1. They encrypt redistributed routes
2. They increase interface bandwidth
3. They can identify the origin or redistribution history of routes so policy can prevent them from being re-imported improperly
4. They replace route metrics

Correct Answer: 3. They can identify the origin or redistribution history of routes so policy can prevent them from being re-imported improperly

Explanation:

A route tag is metadata that can be attached to a route and later matched by routing policy. During mutual redistribution, an administrator can apply a specific tag when routes enter a routing domain. At the opposite redistribution point, policy can deny routes carrying that tag so they are not injected back into the protocol from which they originally came. This is a common technique for controlling redistribution loops in complex networks. Tags do not encrypt routes or replace routing metrics; they provide policy context that allows routers to distinguish routes according to their prior processing history.

Question 377. What is a PRIMARY advantage of using BGP communities for routing policy instead of maintaining separate prefix lists for every policy group?

1. Communities automatically create physical links
2. Communities replace the need for IP prefixes entirely
3. Communities encrypt BGP routes
4. Communities let multiple routes be tagged and processed consistently as a logical group**

Correct Answer: 4. Communities let multiple routes be tagged and processed consistently as a logical group

Explanation:

BGP communities provide a scalable way to classify routes. Instead of writing a long list of individual prefixes in every downstream policy, an operator can attach the same community value to all routes that should receive similar treatment. Other routers can then match the community and apply the appropriate Local Preference, advertisement restriction, or other supported action. This makes policy easier to maintain when prefixes change but their business role remains the same. Huawei BGP supports standard community attributes and well-known values such as No_Export, enabling both custom and standardized policy behavior.

Question 378. What does the BGP network method provide compared with broadly importing an entire routing protocol into BGP?

1. More precise injection of explicitly specified routes into the BGP routing table
2. Automatic advertisement of every route on the router
3. Replacement of BGP route selection
4. Automatic creation of a default route on all peers

Correct Answer: 1. More precise injection of explicitly specified routes into the BGP routing table

Explanation:

Huawei distinguishes two common ways of introducing routes into BGP: importing routes by protocol type and using the network method. Protocol import can bring routes learned through an entire source protocol, such as OSPF or static routing, subject to policy. The network method is more precise because the administrator specifies the exact prefix to introduce into BGP. This can reduce the risk of unintentionally advertising large numbers of internal routes. In both cases, route-policy can be used to filter or modify the routes before they enter the BGP routing table.

Question 379. A route-policy contains several if-match as-path-filter references in the same matching statement. What relationship does Huawei document between those AS_Path filters?

1. XOR
2. OR
3. They are always processed as a numeric sum
4. Only the final filter is evaluated

Correct Answer: 2. OR

Explanation:

Huawei documents that when multiple AS_Path filters are referenced by the same if-match as-path-filter command, the relationship between those filters is OR. Therefore, if a BGP route matches any one of the referenced AS_Path filters, it satisfies that matching condition. This allows one route-policy node to cover several acceptable or interesting AS_Path patterns without requiring a separate route-policy node for each filter. Administrators should still design the underlying regular expressions carefully because overly broad AS_Path patterns can unintentionally match routes that were not meant to be included.

Question 380. An enterprise receives BGP routes from two providers. It wants to accept only approved prefixes, prefer selected routes through one provider, prevent accidental advertisement of internal prefixes, and avoid redistribution loops between BGP and OSPF. Which design BEST meets these requirements?

1. Accept and advertise all routes without policy
2. Use only interface ACLs
3. Use IP prefix lists and BGP import/export route-policies, modify attributes such as Local Preference for path control, and use filtering or route tags when redistributing with OSPF
4. Disable BGP and rely entirely on STP

Correct Answer: 3. Use IP prefix lists and BGP import/export route-policies, modify attributes such as Local Preference for path control, and use filtering or route tags when redistributing with OSPF

Explanation:

The requirements call for coordinated routing policy rather than packet filtering alone. IP prefix lists can precisely identify approved routes. BGP import policies control which provider routes are accepted and can modify attributes such as Local Preference to influence outbound path selection. Export policies prevent sensitive internal prefixes from being advertised externally. Finally, controlled redistribution between OSPF and BGP should use explicit filters and, where useful, tags that identify redistributed routes so they are not accidentally reintroduced into their original routing domain. This produces a safer and more predictable routing design than broad bidirectional redistribution without policy.