350-501 Automation and Assurance Practice Test 1 — 15 Questions

Question 1

Which tool is used to validate YANG data models against device capabilities and to generate Python bindings for automation scripts?

Accepted Answer

pyang. B is correct because pyang is a YANG data modeling language validator and converter that can validate YANG modules against device capabilities (e.g., via RFC 7895 YANG Library) and generate Python bindings (e.g., using the `--plugindir` or `pyang --format pybind` options) for use in automation scripts. It directly supports the task of validating YANG models and producing Python code, unlike the other options which are protocols or automation frameworks.

Answer

RESTCONF

Answer

Ansible

Answer

NETCONF

Question 2

A network engineer is automating BGP configuration using the Cisco IOS-XE YANG model. They want to enable the 'always-compare-med' feature under BGP. Which XPath expression correctly targets this leaf?

Accepted Answer

/native/router/bgp/scope/global/always-compare-med. The Cisco IOS-XE native YANG model (urn:cisco:params:xml:ns:yang:cisco-native) structures BGP configuration under /native/router/bgp/scope/global/always-compare-med. The 'scope' container is required to differentiate between global and VRF-specific BGP settings, and 'always-compare-med' is a leaf within the global scope. This path accurately reflects the hierarchical model used by Cisco for BGP automation.

Answer

/bgp/global/always-compare-med

Answer

/native/router/bgp/always-compare-med

Answer

/router/bgp/global/always-compare-med

Question 3

A service provider uses RESTCONF to automate interface configuration. They need to add a new IPv4 address to an existing interface. Which HTTP method and URI should be used?

Accepted Answer

PATCH /restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet0/1/ietf-ip:ipv4/address. PATCH is the appropriate HTTP method for a partial update to an existing resource, and the URI targets the IPv4 address list under the specific interface. This allows adding a new IPv4 address without replacing the entire interface configuration, which aligns with RESTCONF's support for partial resource modification as defined in RFC 8040.

Answer

DELETE /restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet0/1

Answer

POST /restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet0/1/ietf-ip:ipv4

Answer

PUT /restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet0/1/ietf-ip:ipv4/address

Question 4

A service provider is deploying a new automation framework using Ansible to configure MPLS VPNs. They need to ensure that the Ansible playbook can handle configuration rollback in case of failure. Which Ansible feature should be used?

Accepted Answer

Use the 'backup' option in the ios_config module. The 'backup' option in the ios_config module instructs Ansible to save a copy of the running configuration to a local file before making any changes. If the playbook fails or produces an undesired state, the operator can restore the device to the previous configuration using that backup file. This provides a straightforward rollback mechanism for MPLS VPN deployments without requiring external version control or manual snapshots.

Answer

Use 'tags' to selectively apply tasks

Answer

Use 'check_mode' to validate changes before applying

Answer

Set 'ignore_errors' to true

Question 5

A network engineer is troubleshooting a NETCONF session that fails to establish between a controller and a router. The router supports NETCONF over SSH on port 830. The controller can reach the router but the session fails. What is the most likely cause?

Accepted Answer

The SSH host key of the router is not in the controller's known_hosts file. The most likely cause is that the SSH host key of the router is not in the controller's known_hosts file. NETCONF over SSH (RFC 6242) requires SSH transport, and the controller must authenticate the router's SSH host key during session establishment. If the host key is missing or mismatched, the SSH handshake fails, preventing the NETCONF session from starting, even though the router is reachable and NETCONF is enabled.

Answer

The router's NETCONF capability is disabled

Answer

The controller is using the wrong port (e.g., 22)

Answer

The router does not support YANG models

Question 6

You are a network automation engineer for a large service provider. Your team is tasked with automating the provisioning of new MPLS L3VPN services across a multi-vendor environment (Cisco and Juniper). The automation framework uses Ansible with Jinja2 templates and NETCONF as the transport protocol. During a pilot deployment, the automation successfully configures the Cisco devices but fails on Juniper devices with a 'syntax error' when applying the generated XML configuration. The Jinja2 templates are designed to generate Cisco-style configuration. You need to modify the automation to support both vendors. Which approach is most effective?

Accepted Answer

Use IETF YANG models and create separate Jinja2 templates for Cisco and Juniper that map to their respective native YANG models.. Using IETF YANG models (e.g., RFC 8299 for L3VPN) provides a vendor-neutral data model that both Cisco and Juniper support via NETCONF. Creating separate Jinja2 templates for each vendor ensures the generated XML conforms to each device's native YANG models, avoiding syntax errors. This approach maintains automation consistency while respecting vendor-specific implementations.

Answer

Write a Python script that translates Cisco XML to Juniper XML before sending.

Answer

Switch to CLI-based automation using SSH to avoid XML syntax issues.

Answer

Create a single Jinja2 template that uses conditional statements to generate different XML for each vendor.

Question 7

You are responsible for network assurance for a Tier-1 ISP that has deployed model-driven telemetry using gNMI with ON_CHANGE subscriptions on all core routers. Recently, the NMS team reported that some BGP route flaps are not being captured in the telemetry data, even though the routers' syslogs show the flaps occurred. The telemetry subscription is for the path '/bgp/neighbors/neighbor/state/messages/received'. The NMS is using a gNMI collector that supports both ON_CHANGE and SAMPLE subscriptions. You suspect the issue is with the subscription configuration. Upon reviewing the router configuration, you see that the telemetry subscription uses the SAMPLE mode instead of ON_CHANGE. What is the most appropriate action to ensure all BGP route flap events are captured?

Accepted Answer

Modify the subscription to use ON_CHANGE mode for the BGP neighbor paths.. The gNMI ON_CHANGE subscription mode is designed to stream telemetry updates only when the value of a subscribed path changes. Since the NMS is missing BGP flap events, the subscription must be using SAMPLE mode, which periodically polls the state and can miss transient events between sampling intervals. Changing the subscription to ON_CHANGE ensures that every state transition (e.g., BGP session up/down) is immediately pushed to the collector, capturing all flaps.

Answer

Configure the router to send syslogs to the NMS and parse them for BGP flaps.

Answer

Add a second subscription with ON_CHANGE for the same paths to ensure redundancy.

Answer

Change the subscription to SAMPLE with a 1-second interval to capture flaps more frequently.

Question 8

Match each multicast protocol to its role.

Accepted Answer

IGMP: Manages multicast group membership between hosts and local routers. These are essential multicast protocols for service provider IPTV and content delivery.

Answer

IGMP: Builds distribution trees for efficient multicast forwarding

Answer

PIM-SM: Shares active source information between different domains

Question 9

A network engineer wants to automate the backup of router configurations using Python and NETCONF. Which YANG model should the engineer use to access the running configuration?

Answer

urn:ietf:params:netconf:capability:rollback-on-error:1.0

Answer

urn:ietf:params:netconf:capability:candidate:1.0

Answer

urn:ietf:params:netconf:capability:confirmed-commit:1.0

Answer

urn:ietf:params:netconf:capability:xpath:1.0

Answer

urn:ietf:params:netconf:capability:writable-running:1.0

Question 10

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` (enabled via the `--check` flag or `check_mode: yes`) allows Ansible to first verify device reachability and then compare the intended configuration against the running configuration without making changes. Only when a difference is detected and `check_mode` is disabled will the module apply the configuration changes. This directly meets the requirement of applying configurations only when the device is reachable and the current configuration differs from the intended.

Answer

ios_system

Answer

net_get

Answer

ios_command

Answer

ios_facts

Question 11

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. The collector can establish a gRPC-TLS connection but receives empty data because the sensor-group path 'openconfig-interfaces' is not supported on the Cisco XR router. Cisco IOS XR supports OpenConfig paths only if the corresponding YANG models are loaded and the device implements those models; if the path is unsupported, the router will accept the subscription but send no telemetry data for that path. This is a common misconfiguration when using gRPC telemetry with OpenConfig models on platforms that may not fully support all OpenConfig paths.

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 12

Which TWO are possible causes for a NETCONF session failing to establish with a Cisco IOS-XE device?

Accepted Answer

TCP port 830 is blocked by a firewall. Option D is correct because NETCONF over SSH uses TCP port 830 by default, so a firewall blocking that port prevents the session from ever being established. Option E is correct because NETCONF must be explicitly enabled on the IOS-XE device (for example, with the 'netconf-yang' command) and SSH must be configured to support the NETCONF subsystem; without this, the session cannot be established. Option A is not correct because IOS-XR is a different operating system, not a cause of a NETCONF session failure on an IOS-XE device. Option B is not correct because an incorrect YANG module namespace would affect data modeling or RPC payloads, not the initial NETCONF session establishment. Option C is not correct because NTP synchronization is not required for NETCONF session establishment.

Answer

The device is running IOS-XR

Answer

The YANG module namespace is incorrect

Answer

NTP is not synchronized

Question 13

Refer to the exhibit. A telemetry subscription is configured on an IOS-XR router. The collector at 10.1.1.100 is not receiving data. Which configuration error is present?

Accepted Answer

Missing 'protocol' specification in the destination-group. In IOS-XR telemetry, a destination-group must include the 'protocol' keyword (e.g., 'protocol grpc' or 'protocol tcp') to specify the transport protocol for the collector. Without this specification, the router does not know how to send the telemetry data, and the collector at 10.1.1.100 will not receive any data.

Answer

The destination IP address is incorrect

Answer

The sample-interval is too short

Answer

The subscription is not committed

Answer

The sensor-group path is invalid

Question 14

Refer to the exhibit. An engineer configures IP SLA for UDP jitter. The operation completes successfully, but the customer reports voice quality issues. What should the engineer check next?

Accepted Answer

The threshold is set too high. The IP SLA UDP jitter operation completed successfully, meaning the destination is reachable and the operation is running. However, if the threshold is set too high, the IP SLA will not trigger a reaction (e.g., an SNMP trap or route change) even when jitter exceeds acceptable levels for voice quality. The customer reports voice quality issues, so the engineer must check if the jitter threshold is configured too high, masking the problem.

Answer

The packet loss is 0%

Answer

The frequency is too low

Answer

The jitter value is within threshold

Answer

The destination is unreachable

Question 15

An SP engineer is configuring model-driven telemetry (MDT) to monitor interface utilization on Cisco routers. The telemetry receiver uses gRPC and is experiencing high CPU load due to excessive subscription data. Which MDT subscription parameter should be adjusted to reduce the data rate without losing critical threshold events?

Accepted Answer

Enable on-change reporting with suppression.. Enabling on-change reporting with suppression allows the router to send telemetry data only when a monitored value changes beyond a suppression threshold, drastically reducing data volume while still capturing critical threshold events. This is ideal for reducing CPU load on the receiver without missing important changes.

Answer

Use a smaller path XPath.

Answer

Increase the sensor-group period.

Answer

Increase the sample-interval.