350-501 Practice Test 22 — 15 Questions

Question 1

An engineer is troubleshooting BGP convergence. The router has multiple paths for a prefix, but it selects a path with a lower local preference over a path with a higher local preference. The higher local preference path is from an EBGP peer. What could cause this?

Accepted Answer

The path with lower local preference has a higher weight.. Option D is correct because if the router is configured with 'bgp bestpath compare-routerid', the router ID can override local preference if all other attributes are equal? No, local preference is compared before router ID. Actually, weight is compared first. If the lower local preference path has a higher weight, it wins. So option A (weight) is also plausible. But we need to be specific: The scenario says lower local preference is chosen over higher local preference. The only way is if weight is higher on the lower local preference path. So option A is correct. But we also have option D: 'The router was configured with 'bgp deterministic-med'? That affects MED comparison, not local preference. So let's rethink: Actually, weight is compared first. So if the lower local preference path has a higher weight, it will be chosen. So correct is A. But we need to vary positions. Let's set correct as A. But we have A already used in Q1, Q6. Let's change Q9 to correct B? Let's use 'The router has a higher weight on the lower local preference path' as B. So correct B. Alternatively, we can make the correct answer 'The path with lower local preference was received from a peer with a higher weight' which is B. So set B as correct. Options: A: The router has a lower MED on that path. B: The router has a higher weight on that path. C: The router has a higher router ID on that path. D: The router has 'bgp deterministic-med' enabled. Correct: B.

Answer

The router is configured with 'bgp deterministic-med'.

Answer

The path with lower local preference has a higher router ID.

Answer

The path with lower local preference has a lower MED.

Question 2

An engineer is using RESTCONF to configure an interface on a Cisco IOS-XE device. The request returns a 400 Bad Request error. What is the most likely cause?

Accepted Answer

The JSON payload contains incorrect data types or missing mandatory leafs. A 400 Bad Request typically indicates a client error, such as invalid JSON payload, missing mandatory fields, or incorrect data types. If the module is not supported, a 404 would be returned. Authentication errors result in 401. Incorrect URI gives 404. Privilege issues give 403 or 401.

Answer

The device does not support RESTCONF

Answer

The user does not have sufficient privileges

Answer

The URI is incorrect

Answer

The YANG module is not loaded

Question 3

Which TWO conditions must be met for a BGP route to be considered valid and used for forwarding?

Accepted Answer

The route must be the best path selected by BGP.. Options A and D are correct. A valid BGP route must have a reachable next-hop (A) and must be the best path for the prefix (D). Option B is not required; synchronization is not needed in modern networks. Option C is incorrect; the prefix must be in the routing table, not the BGP table. Option E is incorrect; AS path loop detection is inherent, but not a validity condition per se.

Answer

The BGP synchronization must be enabled.

Answer

The AS path must not contain the router's own AS.

Answer

The prefix must be in the BGP table.

Question 4

A team uses Ansible to automate configuration of Cisco devices. They want to ensure that configurations are applied only if the device is reachable and the current configuration differs from the intended. Which Ansible module or feature is best suited for this?

Accepted Answer

ios_config with check_mode. The ios_config module with check_mode and diff is idempotent: it compares the intended config with the current and applies only if there is a difference. ios_command runs arbitrary commands without idempotency. ios_system and ios_facts are for specific settings or information gathering. net_get retrieves files.

Answer

ios_system

Answer

net_get

Answer

ios_command

Answer

ios_facts

Question 5

Which THREE of the following are characteristics of Segment Routing (SR-MPLS) compared to traditional MPLS with LDP?

Accepted Answer

The IGP (IS-IS or OSPF) is used to advertise prefix SIDs.. Options A, C, and E are correct. SR-MPLS does not require LDP (A), uses IGP to distribute labels (C), and supports traffic engineering via segment lists (E). Option B is incorrect; LDP uses multicast for discovery, but SR-MPLS uses IGP flooding, not multicast. Option D is incorrect; LDP can be used for both transit and egress.

Answer

It can only be used for transit, not for egress routers.

Answer

Labels are distributed via multicast to all routers.

Question 6

An engineer configures model-driven telemetry on a Cisco XR router to send data to a collector. After configuring, the collector receives no data. The engineer verifies that the collector IP and port are reachable. What is the next step to troubleshoot?

Accepted Answer

Check that the sensor-group and destination-group are correctly associated and committed in the subscription. A common misconfiguration is that the sensor-group and destination-group are not properly associated under the subscription. The telemetry configuration requires a subscription that links a sensor-group with a destination-group. Without correct association, no data is sent. SNMP, routes, YANG model validity, or reboot are not the immediate next step.

Answer

Check if the YANG model is valid

Answer

Verify that the router has a route to the collector

Answer

Reboot the router

Answer

Check the SNMP community strings

Question 7

A service provider plans to deploy automation using Cisco NSO. Which two benefits does NSO provide for service lifecycle management? (Choose two.)

Accepted Answer

Automatic rollback on failed deployment.. NSO provides multi-vendor device support via its NETCONF and CLI adapters, and it offers automatic rollback on failed deployments to ensure consistency. Compliance checks and traffic monitoring are not core NSO features, and on-device scripting is not a benefit of NSO itself.

Answer

On-device scripting engine.

Answer

Real-time traffic monitoring.

Answer

Built-in configuration compliance checks.

Question 8

A large SP plans to deploy SR-TE tunnels across the backbone using an SDN controller for path computation. To ensure fast convergence and scalability, which automation approach should be used for tunnel creation?

Accepted Answer

PCEP with stateful delegation to controller. PCEP with stateful delegation allows the controller to compute and update paths dynamically, providing fast convergence and scalability. Static configuration lacks automation, RSVP-TE is not SR-based, NetFlow is for monitoring, and SNMP traps are for alerts, not tunnel creation.

Answer

Static configuration on each router

Answer

RSVP-TE tunnels

Answer

NetFlow-based path selection

Answer

SNMP traps

Question 9

Which THREE are valid reasons for using the 'ipv6 unicast-routing' command on a Cisco router?

Accepted Answer

It enables global IPv6 routing.. Options B, D, and E are correct. This command enables IPv6 routing globally (B), enables IPv6 CEF (D), and allows configuration of IPv6 routing protocols (E). Option A is incorrect; it does not enable IPv6 on interfaces. Option C is incorrect; IPv6 is enabled by default on some platforms, but the command does not enable multicast routing.

Answer

It enables IPv6 on all interfaces.

Answer

It enables IPv6 multicast routing.

Question 10

A Cisco XR router is configured to stream telemetry via gRPC with TLS. The collector can connect but receives empty data. The telemetry configuration is as follows: sensor-group with 'openconfig-interfaces' paths. What is the likely cause?

Accepted Answer

The sensor-group path is not supported by the device. If the device does not support the 'openconfig-interfaces' YANG model, the sensor path returns no data, resulting in empty telemetry data. The collector connects successfully, so TLS is fine. Missing encoding would cause errors but not empty data. CPU overload or short interval would still produce some data.

Answer

The router's CPU is overloaded

Answer

The collector does not support TLS

Answer

The telemetry interval is too short

Answer

The destination group is missing the 'encoding' configuration

Question 11

An automation engineer uses RESTCONF to configure a Cisco ASR 9000 router. When sending a PATCH request to update an interface description, the API returns 404 Not Found. What is the most probable issue?

Accepted Answer

The interface does not exist on the device.. HTTP 404 indicates the requested resource is not found. For a PATCH on an interface, the most likely cause is that the interface does not exist. Other options would result in different HTTP status codes.

Answer

HTTP authentication is required.

Answer

The YANG module is not supported.

Answer

The RESTCONF username/password is incorrect.

Question 12

When automating configuration changes across a large network using a tool like Cisco NSO, what is the best practice to minimize the risk of negative impact?

Accepted Answer

Use a staging environment with identical configuration to test before production. Using a staging environment with identical configuration allows comprehensive testing before production deployment, minimizing risks. While maintenance windows and rollback are useful, they are reactive rather than proactive. Applying directly to production is risky. Limiting to read-only avoids changes altogether, which is not the goal.

Answer

Rely on rollback automation

Answer

Limit automation to read-only commands

Answer

Automate only during maintenance windows

Answer

Apply changes directly to production devices

Question 13

A service provider is implementing QoS policies on an access aggregation router. They want to shape traffic to a downstream DSLAM to 10 Mbps, but they do not want to exceed the shaping rate even if the line rate is higher. Which QoS tool should be used on the interface facing the DSLAM?

Accepted Answer

Shaping. Option C is correct. Shaping buffers traffic to a configured rate, smoothing bursts and ensuring the rate is not exceeded. Option A (Policing) drops or marks traffic that exceeds a rate, but does not buffer. Option B (Marking) sets DSCP/IP precedence but does not enforce rate. Option D (Queuing) manages congestion but not rate enforcement.

Answer

Queuing

Answer

Marking

Answer

Policing

Question 14

Which TWO are benefits of model-driven telemetry over SNMP polling?

Accepted Answer

Supports structured data models (YANG). Model-driven telemetry reduces CPU usage by pushing data instead of polling, and it uses structured data models (YANG) for better programmability. SNMP uses UDP and unstructured data. XML exclusivity is not a benefit as telemetry supports multiple encodings. Fewer credentials and legacy compatibility are not inherent benefits.

Answer

Requires fewer credentials for access

Answer

Works with legacy devices without modification

Answer

Uses XML exclusively

Question 15

Refer to the exhibit. Which of the following is true about the BGP table?

Accepted Answer

The prefix 192.168.3.0/24 has two paths, with the best path selected based on some attribute.. Option A is correct because only the prefix 192.168.3.0/24 has two paths, one marked with '>' (best) and one without. Options B, C, and D are incorrect: the '?' indicates incomplete origin, the route with lower local preference is not always best, and AS path 300 400 is longer.

Answer

The route to 192.168.3.0/24 with path 300 400 has an origin of IGP.

Answer

The prefix 192.168.2.0/24 is not the best path because it has a lower local preference.

Answer

The route to 192.168.3.0/24 via 10.4.4.4 is the best path because it has a shorter AS path.