350-501 Practice Test 5 — 10 Questions

Question 1

Based on the exhibit, what is the purpose of the 'mpls ldp neighbor ... password cisco' commands?

Accepted Answer

To authenticate the LDP session using MD5.. The 'mpls ldp neighbor ... password cisco' command configures a Message Digest 5 (MD5) authentication password for the LDP session with a specific neighbor. This ensures that the TCP connection used for LDP exchanges is authenticated, preventing spoofed or unauthorized LDP messages from being accepted, as defined in RFC 5036.

Answer

To synchronize LDP and IGP convergence.

Answer

To control the label allocation for prefixes from that neighbor.

Answer

To enable LDP session protection for the neighbor.

Question 2

Based on the exhibit, why is the route 10.10.10.0/24 from remote PE not installed in the VRF Customer-A on PE1?

Accepted Answer

The VRF imports route-target 200:200, but the route has RT 100:100. The route has RT 100:100, but VRF Customer-A imports RT 200:200. Thus, the route is not imported. Option A is wrong because the localpref is 100, which is default and not an issue. Option C is wrong because the RD mismatch is between VRFs, but RD does not affect import; RT does. Option D is wrong because label allocation is working fine (vpn-label:24000).

Answer

The localpref is too low (100)

Answer

The MPLS label allocation failed on the remote PE

Answer

The route distinguisher on the VRF (100:1) does not match the remote RD

Question 3

Which TWO of the following are characteristics of MPLS-TE (Traffic Engineering)?

Accepted Answer

Uses explicit paths to route traffic away from shortest-path IGP.. MPLS-TE uses explicit paths (either strict or loose) to direct traffic away from the shortest path determined by the IGP (e.g., OSPF or IS-IS). This allows network operators to engineer traffic flows based on administrative policies, such as load balancing or avoiding congested links, rather than relying solely on the IGP's metric-based shortest path.

Answer

Uses LDP for label distribution along the TE tunnel.

Answer

Requires per-platform label space for TE tunnels.

Answer

Requires all routers in the TE tunnel to be in the same OSPF area.

Question 4

Match each BGP attribute to its category or purpose.

Accepted Answer

Local Preference: Well-known discretionary attribute used for outbound traffic influence. Correct matches associate BGP attributes with their standard categories and purposes. Local Preference and Next Hop are well-known discretionary and mandatory respectively, while MED is optional nontransitive. Common confusions include misclassifying attribute categories or purposes.

Answer

Local Preference: Optional transitive attribute used to tag routes

Answer

AS Path: Optional nontransitive attribute used for inbound traffic influence

Question 5

Drag and drop the steps to configure a static route on a Cisco IOS router into the correct order.

Accepted Answer

1. Enter global configuration mode (configure terminal)
2. Configure the static route using the ip route command with destination network, subnet mask, and next-hop address or exit interface
3. Verify the configuration (e.g., show ip route)
4. Exit configuration mode (end or exit). Static routes require global config mode and must specify the destination network, subnet mask, and next-hop address or exit interface.

Answer

1. Enter global configuration mode (configure terminal)
2. Verify the configuration (e.g., show ip route)
3. Configure the static route using the ip route command
4. Exit configuration mode (end or exit)

Answer

1. Configure the static route using the ip route command
2. Enter global configuration mode (configure terminal)
3. Verify the configuration (e.g., show ip route)
4. Exit configuration mode (end or exit)

Answer

1. Exit configuration mode (end or exit)
2. Enter global configuration mode (configure terminal)
3. Configure the static route using the ip route command
4. Verify the configuration (e.g., show ip route)

Question 6

A service provider is migrating from LDP to Segment Routing. What is the correct order of operations to ensure uninterrupted MPLS forwarding?

Accepted Answer

Enable SR on each router one by one while LDP remains active, then remove LDP after SR is stable.. It follows the recommended migration strategy of running LDP and Segment Routing (SR) in parallel. By enabling SR on each router one by one while LDP remains active, MPLS forwarding continues uninterrupted via LDP until SR is fully deployed and stable. Once SR is verified on all routers, LDP can be safely removed without causing any forwarding black holes.

Answer

Enable SR on all routers simultaneously.

Answer

Configure IS-IS SR extensions on all routers, then disable LDP.

Answer

Disable LDP first to free labels, then enable SR.

Question 7

A large service provider operates an MPLS L3VPN network with multiple Route Reflectors (RRs) in the core. The network uses BGP as the control plane for both IPv4 unicast and VPNv4 routes. Recently, one of the RRs started flapping, causing route withdrawals to many clients. The network architect wants to improve stability. The RRs are fully meshed with each other and clients are configured as route-reflector clients. The RRs have both IPv4 and VPNv4 address families enabled. Which action should be taken to minimize the impact of an RR failure?

Accepted Answer

Configure client-to-client reflection on the RRs and ensure that each PE is a client of at least two RRs.. Configuring client-to-client reflection on the RRs and ensuring each PE is a client of at least two RRs provides redundancy; if one RR fails, routes are still available via the other RR. BGP PIC helps fast failover but does not prevent route withdrawal impact; add-paths increases paths but not redundancy; same cluster ID reduces redundancy.

Answer

Configure BGP prefix-independent convergence (PIC) on all PE routers.

Answer

Implement BGP add-paths capability on RRs to advertise multiple paths to clients.

Answer

Deploy redundant RRs with the same cluster ID and use the 'bgp cluster-id' command to ensure clients only accept routes from one RR at a time.

Question 8

An SP router is configured with a hierarchical QoS policy (parent policy shaper, child policy with CBWFQ). When applying this policy to an interface, the router reports 'Policy map not found' error. What is the most likely cause?

Accepted Answer

The child policy-map specified in the parent's 'service-policy' command does not exist.. The 'Policy map not found' error occurs when the parent policy-map references a child policy-map via the 'service-policy' command, but that child policy-map does not exist in the router's configuration. Hierarchical QoS requires both the parent and child policy-maps to be created and correctly named; a missing child policy-map prevents the router from applying the nested policy.

Answer

The interface speed is not configured.

Answer

The interface is not part of a bridge domain.

Answer

The shape average command in the parent policy uses an unsupported value.

Question 9

During a maintenance window, an automation script pushed a QoS policy that inadvertently changed the marking for all inbound traffic on a core interface. The change was rolled back, but performance reports show that some traffic is still being marked incorrectly. What is the most logical explanation?

Accepted Answer

The rolled back policy was applied inbound, but the outbound policy that also applies marking was not rolled back. QoS policies can be applied independently in the inbound and outbound directions on an interface. If the original automation script modified the inbound marking policy, and the rollback only reverted that inbound policy, any outbound policy that also performs marking would remain unchanged and continue to incorrectly mark traffic. This explains why some traffic still shows incorrect marking after the rollback.

Answer

The automation script used RESTCONF which requires a commit to finalize

Answer

The device requires a reload to clear the old marking

Answer

The rollback script only applied to the outbound direction

Question 10

A service provider uses a centralized automation system to manage QoS policies via NETCONF and YANG. When attempting to push a new policy-map, the device returns an error indicating that the policy-map type is not supported in the specified location. What is the most likely cause?

Accepted Answer

The policy-map is being applied to an interface that does not support hierarchical QoS. The error indicates that the policy-map type is not supported in the specified location. This typically occurs when a policy-map is applied to an interface that does not support hierarchical QoS (HQoS), such as a physical interface that requires a service-policy under a parent policy-map. The NETCONF/YANG operation succeeds in syntax but fails due to device-level capability constraints.

Answer

The YANG module for QoS is not installed on the device

Answer

The NETCONF session is not authenticated

Answer

The automation system is using the wrong namespace