350-401 Automation Practice Test 1 — 15 Questions

Question 1

A network engineer needs to automate the backup of running configurations from multiple Cisco IOS XE devices to a central TFTP server. Which tool is best suited for this task in a Python-based automation framework?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Paramiko. Paramiko is a Python library that implements the SSHv2 protocol, allowing direct, low-level SSH connections to network devices. For backing up running configurations to a TFTP server, Paramiko can execute the `copy running-config tftp:` command on each device, providing the necessary interactive session handling. While Netmiko is built on Paramiko, it is a higher-level library that abstracts away some of the low-level control; for a simple, script-driven backup task, Paramiko offers the direct SSH access needed without additional overhead.

Answer

RESTCONF

Answer

Ansible

Answer

Netmiko

Question 2

An organization uses Cisco DNA Center to automate network provisioning. A network engineer deploys a new access switch but finds that the switch does not receive the intended configuration template. The switch appears in DNA Center inventory with status 'Managed'. What is the most likely cause?

Accepted Answer

The switch is not assigned to a site. In Cisco DNA Center, configuration templates are applied based on site assignment. A switch that appears as 'Managed' in inventory has been discovered and is under DNA Center's control, but if it is not assigned to a specific site, DNA Center cannot determine which template to push. Site assignment is a prerequisite for template-based provisioning; without it, the intended configuration will not be deployed.

Answer

The switch has not been discovered by DNA Center

Answer

The switch is not in Plug and Play mode

Answer

The switch does not have a valid DNA license

Question 3

A network team uses Ansible to automate VLAN configuration on Cisco IOS devices. The playbook fails with the error 'Failed to connect to the host via ssh: Permission denied (publickey)'. The control node runs Ubuntu, and the network devices are configured with SSH key authentication. Which solution should the engineer implement?

Accepted Answer

Run ssh-add on the control node to add the private key to the SSH agent. The error 'Permission denied (publickey)' indicates that the SSH key is not being presented to the IOS device. Running ssh-add on the control node loads the private key into the SSH agent, which Ansible uses by default when connecting via SSH. This resolves the authentication failure without requiring a passphrase or changing the inventory.

Answer

Set ansible_ssh_private_key_file in the inventory but omit the passphrase

Answer

Set ansible_user to the correct username in the inventory

Answer

Enable keyboard-interactive authentication on the IOS devices

Question 4

A company uses Cisco Catalyst Center (formerly DNA Center) for intent-based networking. After upgrading the Catalyst Center appliance, the engineer notices that some devices are unreachable via the network, but the Catalyst Center GUI shows them as 'Managed'. What is the most likely cause?

Accepted Answer

The IP address of the Catalyst Center appliance changed after the upgrade. When the Catalyst Center appliance is upgraded, its IP address may change if the upgrade process resets network configuration or if the appliance is redeployed with a new IP. Devices are managed via IP-based communication (e.g., SSH, SNMP, NETCONF), and if the Catalyst Center IP changes, devices will still show as 'Managed' in the GUI because the database retains the device state, but the devices themselves cannot be reached because they are trying to communicate with the old IP address. This mismatch causes unreachability despite the managed status.

Answer

SNMP community strings are misconfigured

Answer

Devices were reassigned to different roles

Answer

Certificate trust between devices and Catalyst Center expired

Question 5

A network engineer is creating a Python script using the Cisco IOS XE RESTCONF API to configure a loopback interface. The script sends a PUT request to the URI /restconf/data/Cisco-IOS-XE-native:native/interface/Loopback=100 with a JSON body that includes the IP address. The API returns a 201 Created status, but the loopback interface does not appear in the running configuration. What is the most likely issue?

Accepted Answer

The PUT request should be a POST request to create a new resource. The 201 Created status indicates that the server accepted the request, but the loopback interface was not actually created because the PUT method is not appropriate for creating a new list resource in the Cisco IOS XE RESTCONF implementation. According to the RESTCONF protocol, POST is used to create a new data resource when the client does not provide the exact resource identifier, while PUT is used to replace or create a resource when the client specifies the entire URI. However, for list entries in YANG data models, some implementations (including Cisco IOS XE) require POST to the list node to create a new instance, as PUT to a specific instance may only be effective if the instance already exists or may be accepted but not committed to the running configuration. Therefore, even though a 201 was returned, the configuration was not applied, indicating that a POST request to /restconf/data/Cisco-IOS-XE-native:native/interface/Loopback would have been the correct approach.

Answer

The RESTCONF API returned an error but the script ignored it

Answer

The loopback interface number is incorrect in the URI

Answer

The script is not authenticated properly

Question 6

A network engineer uses Netmiko to connect to multiple Cisco IOS XE devices and execute commands. The script runs correctly for most devices but fails for one device with the error: 'ValueError: SSH session not active'. The device is reachable and SSH credentials are correct. What is the most likely cause?

Accepted Answer

The device's SSH server is not fully initialized. The error 'ValueError: SSH session not active' indicates that Netmiko attempted to establish an SSH connection but the session was not fully active. The most likely cause is that the device's SSH server is not fully initialized, which can happen if the device is still booting or the SSH process has not completed startup. This is distinct from reachability or credential issues, as the device responds to pings but the SSH daemon is not ready to accept connections.

Answer

The connection timeout is set too low

Answer

The device has reached the maximum number of SSH sessions

Answer

The device requires an enable password but none was provided

Question 7

A company uses Chef to automate network device configuration. The network devices are Cisco IOS XE running in a brownfield environment. Which Chef component is used to manage the state of the devices?

Accepted Answer

Chef client. In a Chef-managed brownfield environment with Cisco IOS XE devices, the Chef client is the agent that runs on each device (or on a proxy like a guest shell) and applies the desired state defined in cookbooks. It is responsible for converging the device's configuration to match the policy, making it the correct component for state management.

Answer

Ohai

Answer

Chef workstation

Answer

Chef server

Question 8

A network engineer is troubleshooting an Ansible playbook that uses the ios_config module to apply ACLs. The playbook runs without errors, but the ACLs are not applied to the device. The engineer verifies that the device is reachable and the credentials are correct. What is the most likely cause?

Accepted Answer

The playbook is missing the connection parameter set to 'network_cli'. The ios_config module requires the connection parameter to be set to 'network_cli' (or 'ansible.netcommon.network_cli') to use the CLI transport for sending configuration commands to network devices. Without this, Ansible defaults to the 'smart' connection, which may not properly interact with network device CLIs, causing the playbook to run without errors but not apply the ACLs.

Answer

The device is in a different VRF and not reachable

Answer

The ACL syntax in the playbook is incorrect

Answer

The ios_config module requires the netmiko library to be installed on the control node

Question 9

Refer to the exhibit. A network engineer wants to use Ansible to change the IP address of Loopback100 from 10.1.100.1/24 to 10.1.200.1/24. The playbook uses the ios_config module. The playbook runs successfully, but the IP address remains unchanged. What is the most likely reason?

Accepted Answer

The ios_config module is not configured to replace the existing configuration. The ios_config module in Ansible, by default, uses a 'set' operation that appends commands to the running configuration. To change an existing IP address on an interface, the module must be configured with the 'replace' option or use a 'before'/'parents' directive to remove the old address first. Without this, the new IP command is added but the old one remains, and the interface retains the original address because Cisco IOS allows multiple IP addresses on a single interface only if the secondary keyword is used, which the module does not automatically apply.

Answer

The loopback interface is administratively down

Answer

The playbook is sending the wrong CLI commands

Answer

The SNMP community strings are not configured correctly

Question 10

Refer to the exhibit. A Python script sends the JSON payload shown via a POST request to the RESTCONF URI /restconf/data/ietf-interfaces:interfaces on a Cisco IOS XE device. The API returns 201 Created, but the interface GigabitEthernet1 is not configured. What is the most likely cause?

Accepted Answer

The payload is missing a required field for the interface. The 201 Created response indicates the RESTCONF request was accepted and the resource was created, but the interface GigabitEthernet1 is not configured because the JSON payload is missing a required field. In the ietf-interfaces YANG model, the 'type' leaf under an interface is mandatory; without it, the device cannot complete the interface configuration, even though the API returns a success status for the creation of the container.

Answer

The script is not authenticated

Answer

The URI should be /restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet1

Answer

The JSON syntax is invalid

Question 11

A company has a large network of 500 Cisco IOS XE routers and switches spread across multiple sites. The network team wants to automate the collection of interface statistics every hour and store them in a central database for historical analysis. The team has a Linux server with Python 3 and access to all devices via SSH with key-based authentication. They have written a Python script using Netmiko to connect to each device, run 'show interfaces', and parse the output to extract key metrics (e.g., input/output errors, packets per second). The script works correctly when tested on a small subset of devices, but when run against all 500 devices, it takes too long (over 2 hours) and sometimes fails due to SSH connection timeouts. The team needs to reduce the execution time and improve reliability. Which approach should they take?

Accepted Answer

Implement multiprocessing or multithreading in the Python script to connect to devices concurrently. The primary bottleneck is sequential SSH connections to 500 devices. By using Python's multiprocessing or multithreading (e.g., concurrent.futures.ThreadPoolExecutor), the script can open multiple SSH sessions in parallel, drastically reducing total wall-clock time. Netmiko itself is not the issue; the serial execution pattern causes the 2-hour runtime and timeouts, which concurrent connections resolve by overlapping I/O wait times.

Answer

Reduce the collection frequency to every 4 hours

Answer

Replace Netmiko with SNMP polling using the pysnmp library

Answer

Use Ansible playbooks instead of a custom Python script

Question 12

A service provider uses Cisco IOS XE routers with NETCONF/YANG for configuration management. They have a centralized automation system that pushes configuration changes via NETCONF. Recently, after a maintenance window, several routers lost connectivity to the NETCONF server. The automation system can still SSH to the routers and execute CLI commands. The engineer suspects that the NETCONF server's SSH key changed, causing the routers to reject the connection. However, checking the routers' configuration, the engineer finds that the 'netconf ssh' command is present and the SSH server is enabled. The engineer also notices that the routers have an 'ip ssh server algorithm publickey' configuration specifying a list of allowed public keys. What is the most likely cause of the NETCONF connectivity loss?

Accepted Answer

The NETCONF server's SSH public key is not in the allowed list on the routers. The routers have an 'ip ssh server algorithm publickey' configuration that explicitly lists allowed public keys. If the NETCONF server's SSH key was changed during the maintenance window, its new public key would not match any entry in this allowed list, causing the routers to reject the SSH connection for NETCONF even though SSH itself is enabled and the 'netconf ssh' command is present. This is a common security hardening practice that restricts which SSH clients can connect.

Answer

The NETCONF server is using a non-standard port

Answer

The routers have reached the maximum number of SSH sessions

Answer

The 'netconf ssh' command was removed from the router configuration

Question 13

A network engineer is automating the deployment of VLANs across multiple switches using Ansible. The playbook runs successfully on most switches, but one switch fails with an error indicating that the VLAN configuration command is not recognized. What is the most likely cause?

Accepted Answer

The switch runs a different IOS version with different VLAN CLI syntax. The most likely cause is that the switch runs a different IOS version with different VLAN CLI syntax. Ansible executes commands via SSH, and if the switch expects a different command format (e.g., 'vlan 10' vs. 'vlan database' on older CatOS), the playbook will fail with a command-not-recognized error. This is a common issue when automating across heterogeneous network devices.

Answer

Ansible lacks the appropriate module for VLAN configuration

Answer

The inventory file has a syntax error for that specific host

Answer

SSH connectivity to the switch is blocked by an ACL

Question 14

A DevOps team is implementing a CI/CD pipeline that automates network configuration changes. Which design principle is most important to ensure that a failed deployment does not cause prolonged outages?

Accepted Answer

Ensure the automation framework supports rollback to a known good state. In a CI/CD pipeline for network automation, the ability to roll back to a known good state is the most critical design principle for minimizing downtime. If a deployment fails (e.g., a misapplied ACL or BGP configuration), the automation framework must be able to revert the network device to its previous stable configuration—often by reapplying a saved startup config or using a tool like Ansible's `network_backup` role or Cisco NSO's rollback mechanism. Without this, a failed deployment could leave the network in a broken state until manual intervention, causing prolonged outages.

Answer

Use a single source of truth for all configurations

Answer

Implement idempotent configuration scripts

Answer

Run the deployment in a lab environment first

Question 15

A network engineer is troubleshooting an automated configuration change that caused a routing loop. The change was pushed via an Ansible playbook that modified OSPF cost values on multiple routers simultaneously. What is the most likely reason for the loop?

Accepted Answer

The changes were applied simultaneously without allowing OSPF to converge between updates. Applying OSPF cost changes simultaneously on multiple routers without allowing convergence between updates can cause transient routing loops. OSPF relies on the SPF algorithm to calculate loop-free paths based on consistent link-state databases across the network. When costs are changed on multiple routers at once, some routers may have outdated LSAs, leading to inconsistent forwarding tables and temporary loops until all routers reconverge.

Answer

OSPF does not support changing costs on multiple routers at the same time

Answer

OSPF uses hop count as a metric, and the changes caused a count-to-infinity issue

Answer

The OSPF cost values were changed to non-standard values that OSPF cannot process