200-901 Practice Test 15 — 15 Questions

Question 1

A DevOps team is implementing a CI/CD pipeline for network services using Cisco NSO (Network Services Orchestrator). They have a Python script that uses the NSO RESTCONF API to create a new VPN service instance. The script passes all integration tests in the staging environment, but when deployed to production, the 'POST' request to /api/run/vpn-service returns a 500 Internal Server Error. The team checks the NSO logs and finds the error 'Error: No such device: device-xr-1'. The production NSO instance manages multiple devices, and device-xr-1 is one of them. The team confirms device-xr-1 is reachable and managed by NSO in the production environment. What is the most likely cause of this error?

Accepted Answer

The YANG service model expects a device name that does not match the device's name in NSO's device list.. The error 'No such device: device-xr-1' indicates that the YANG service model references a device name that does not match the actual device name configured in NSO's device list. Even though device-xr-1 is reachable and managed by NSO, the service model's 'device' leaf expects a specific name (e.g., 'xr-1' or 'device-xr-1-prod'), and the mismatch causes NSO to fail when trying to map the service to the device. This is a common issue when service YANG models are developed with hardcoded or environment-specific device names that differ between staging and production.

Answer

The production NSO instance uses a different authentication method for device-xr-1.

Answer

The device configuration in NSO is out of sync; a sync-from is needed before service creation.

Answer

The production NSO instance has insufficient memory to handle the request.

Question 2

Which THREE of the following are typically included in a Cisco DevNet sandbox environment? (Choose three.)

Accepted Answer

Pre-configured Cisco devices (routers, switches, or firewalls). Option C is correct because Cisco DevNet sandboxes provide pre-configured Cisco devices (routers, switches, firewalls) to allow developers to test automation scripts and network configurations without needing physical hardware. These sandboxes are isolated environments that mirror production-like setups, enabling safe experimentation with device APIs and CLI commands.

Answer

Ability to run production application traffic

Answer

Access to production customer data for realistic testing

Question 3

A network administrator is tasked with automating the deployment of a new VLAN configuration across a fabric of Cisco ACI switches. Which automation tool is best suited for interacting with the APIC REST API?

Accepted Answer

Ansible. Ansible is the best-suited tool because it provides a dedicated module (cisco.aci.aci_rest) that directly interacts with the APIC REST API, allowing declarative automation of VLAN and other ACI configurations. Unlike generic scripting, Ansible abstracts the HTTP requests and handles idempotency, authentication, and error handling natively for the ACI fabric.

Answer

Bash scripting with curl

Answer

Chef

Answer

Puppet

Question 4

A network engineer uses Ansible to apply a standard ACL to multiple routers. The playbook runs without errors, but the ACL is not applied on some routers. Upon checking, those routers have a different configuration revision due to a previous manual change. What is the best practice to ensure consistent application?

Accepted Answer

Use the 'replace' parameter to overwrite the entire config. Option A is correct because the 'replace' parameter in Ansible's ios_config module forces a full configuration replacement on the target device, overwriting the entire running configuration with the intended configuration. This ensures that any prior manual changes or configuration revisions are eliminated, guaranteeing consistent ACL application across all routers regardless of their current state.

Answer

Use the ansible_network_os variable correctly

Answer

Use the 'backup' option in ios_config

Answer

Use the 'ignore_errors' directive

Question 5

In a CI/CD pipeline for network automation, a change is rolled back using a Git revert commit that triggers a new pipeline. The rollback playbook fails because the 'previous' configuration snapshot is missing. What should be implemented to prevent this?

Accepted Answer

Store configuration backups in a version-controlled repository before each change. Storing configuration backups in a version-controlled repository before each change ensures that a known good state is available for rollback, even if subsequent changes occur.

Answer

Use a single source of truth like NetBox

Answer

Use the 'check mode' only

Answer

Disable rollback pipelines

Question 6

A network team uses an Ansible playbook to automate the configuration of multiple Cisco IOS XE devices. The playbook includes the 'ios_config' module. Which of the following best describes the purpose of the 'provider' parameter in the ios_config module?

Accepted Answer

It defines the connection details for the device.. The 'provider' parameter in the ios_config module is a dictionary that encapsulates the connection details required to access the network device, such as hostname, username, password, port, and transport protocol (e.g., SSH). This allows the module to establish a session with the Cisco IOS XE device before applying configuration changes. Without the provider, the module would not know how to reach or authenticate to the target device.

Answer

It identifies the name of the playbook being used.

Answer

It specifies the configuration lines to be applied.

Answer

It sets the timeout for the module execution.

Question 7

Which tool is designed for infrastructure as code, uses a declarative language, and can automate configuration management across multiple devices?

Accepted Answer

Ansible. Ansible is the correct answer because it is an infrastructure-as-code tool that uses a declarative YAML-based language (playbooks) to define desired system states. It automates configuration management across multiple devices agentlessly, using SSH or WinRM to push configurations, making it ideal for multi-device environments.

Answer

Git

Answer

Python

Answer

Postman

Question 8

A developer is creating a YANG data model for a new interface feature. The model must allow the user to choose from a predefined set of values for the 'duplex' leaf. Which YANG statement should be used to restrict the values to 'full', 'half', and 'auto'?

Accepted Answer

type enumeration { enum full; enum half; enum auto; }. Option D is correct because the 'type enumeration' statement in YANG defines a leaf that can only take one of the explicitly listed enum values. By specifying 'enum full;', 'enum half;', and 'enum auto;', the developer restricts the 'duplex' leaf to exactly those three predefined strings, which matches the requirement.

Answer

choice duplex-options { case full; case half; case auto; }

Answer

type string;

Answer

type leafref { path '/other:duplex-list'; }

Question 9

Refer to the exhibit. Based on the YANG model snippet, what is the data type of the 'mask' leaf?

Accepted Answer

inet:ipv4-prefix-length. The 'mask' leaf is defined with the type 'inet:ipv4-prefix-length', which represents a decimal integer from 0 to 32 indicating the number of leading 1 bits in the subnet mask (e.g., 24 for /24). This is the correct data type for a prefix length in YANG models, not an IPv4 address or a generic string.

Answer

inet:ipv4-address

Answer

uint8

Answer

string

Question 10

A network administrator is managing a small office with 10 Cisco 9200 switches. They want to automate the deployment of a standard base configuration (VLANs, STP, management access) to all switches. They have a Linux server with Ansible installed. The administrator writes a playbook that uses the 'ios_config' module to apply configuration blocks. However, when they run the playbook against the first switch, it fails with an authentication error. The administrator can SSH to the switch manually using the same credentials. What is the most likely cause of the failure?

Accepted Answer

The Ansible playbook is missing the 'ansible_connection: network_cli' and 'ansible_network_os: ios' variables.. For Ansible to connect to network devices, the connection type must be set to 'network_cli' and the network OS must be specified. Without these, Ansible may attempt to use the default SSH connection method (paramiko) which does not handle network device prompts correctly, leading to authentication errors.

Answer

The switch's SSH server does not support the key exchange algorithm used by Ansible.

Answer

The playbook is using the wrong username because the variable is not defined.

Answer

The switch is running an incompatible IOS version that does not support the commands in the playbook.

Question 11

When using the Cisco Meraki Dashboard API to create an HTTP webhook for network alerts, which authentication method is required in the request header?

Accepted Answer

X-Cisco-Meraki-API-Key: <your_api_key>. The Cisco Meraki Dashboard API requires authentication via a custom HTTP header named `X-Cisco-Meraki-API-Key`, where the value is your API key. This is the only supported method for authenticating requests to the Meraki API, as documented in the official API reference. Option D correctly specifies this header, making it the required authentication method for creating an HTTP webhook for network alerts.

Answer

Authorization: Bearer <token>

Answer

Include the API key as a query parameter.

Answer

Authorization: Basic <base64>

Question 12

Which THREE are common best practices for implementing CI/CD in network automation?

Accepted Answer

Use version control for all automation scripts and playbooks. Option B is correct because version control (e.g., Git) is a fundamental CI/CD best practice: it tracks changes, enables rollbacks, and supports collaboration on automation scripts and playbooks. Without version control, you lose auditability and the ability to reliably reproduce network states, which violates the principle of infrastructure as code.

Answer

Perform manual testing after every deployment

Answer

Store credentials and secrets in code repositories

Question 13

A DevOps engineer is implementing Infrastructure as Code (IaC) for network devices. Which of the following practices is most critical to ensure that the environment state matches the desired configuration defined in code?

Accepted Answer

Ensuring that the automation tool is idempotent.. Idempotency ensures that applying the same configuration multiple times always results in the same desired state, regardless of the current state of the device. This is the most critical practice for IaC because it prevents configuration drift and guarantees that the environment state matches the code-defined configuration. Without idempotency, repeated runs of the automation tool could introduce unintended changes or fail to correct deviations.

Answer

Using Jinja2 templates to generate device configurations.

Answer

Using version control for all configuration files.

Answer

Implementing rollback procedures for failed deployments.

Question 14

Using the Cisco DNA Center API, an engineer wants to create a new site with building and floor information. Which HTTP method and endpoint should be used?

Accepted Answer

POST /dna/intent/api/v1/site. The POST HTTP method is used to create a new resource on the server, and the Cisco DNA Center API endpoint `/dna/intent/api/v1/site` is designed to accept a POST request with a JSON payload containing site, building, and floor details. This follows RESTful conventions where POST is the standard method for resource creation, and the API documentation specifies this exact endpoint for adding a new site hierarchy.

Answer

PUT /dna/intent/api/v1/site

Answer

GET /dna/intent/api/v1/site

Answer

POST /dna/intent/api/v1/site/create

Question 15

Which TWO methods are commonly used to discover network devices in an automation environment? (Select exactly 2.)

Accepted Answer

Using LLDP or CDP to retrieve directly connected neighbor information. Option D is correct because LLDP (IEEE 802.1AB) and CDP (Cisco Discovery Protocol) are Layer 2 protocols that allow network devices to advertise their identity, capabilities, and directly connected neighbors. In automation environments, these protocols enable dynamic discovery of the network topology without manual intervention, making them essential for automated inventory and mapping.

Answer

Manually entering device details into a spreadsheet

Answer

Using SNMP to bulk-configure devices

Answer

Monitoring DHCP logs to lease IP addresses to new devices