200-901 Practice Exam 54 — 20 Questions

Question 1

A developer wants to run a container in the background with port mapping and a named volume. Which command accomplishes this?

Accepted Answer

docker run -d -p 8080:80 -v myvol:/data --name myapp nginx. Options A and C are both correct. Option A uses the `-v` flag to mount a named volume, which is a shorthand for volume mounting. Option C uses the `--mount` flag; when `type=volume` is omitted, it defaults to a volume mount, so `--mount source=myvol,target=/data` is equivalent to `-v myvol:/data`. Both commands create a new container in detached mode (`-d`), map port 8080 on the host to port 80 in the container (`-p 8080:80`), mount the named volume `myvol` to `/data`, and name the container `myapp`. Option B is incorrect because `docker start` only starts an existing container and cannot create a new one or specify port mapping or volumes.

Answer

docker start -d -p 8080:80 -v myvol:/data --name myapp nginx

Question 2

Refer to the exhibit. This JSON response was received from the Cisco DNA Center API. A developer wants to extract the software version of the first device. Which Python expression correctly retrieves '16.12.5' from the variable `data`?

Accepted Answer

data['response'][0]['softwareVersion']. The JSON response from Cisco DNA Center's API is structured with a 'response' key containing an array of device objects. To access the software version of the first device, you must first index into the array with [0] to get the first device object, then use the key 'softwareVersion' to retrieve the value '16.12.5'. The variable `data` holds the entire JSON object, so `data['response'][0]['softwareVersion']` correctly navigates this nested structure.

Answer

data[0]['softwareVersion']

Answer

data['response'][0]['version']

Answer

data['response']['softwareVersion']

Question 3

An automation script needs to update the hostname of a Cisco IOS-XE device via RESTCONF. Which HTTP method is appropriate?

Accepted Answer

PUT. To update the hostname of a Cisco IOS-XE device via RESTCONF, the PUT HTTP method is appropriate because it performs a full replacement of the target resource. RESTCONF uses the YANG data model, and the hostname is a leaf node under the Cisco-IOS-XE-native YANG module. A PUT request with the complete updated hostname data replaces the existing configuration, aligning with RESTCONF's semantics for resource replacement.

Answer

PATCH

Answer

GET

Answer

POST

Question 4

Drag and drop the steps to deploy a Python script to a Cisco device via RESTCONF into the correct order.

Accepted Answer

Authenticate to the device, then construct the RESTCONF URL and headers, then send the HTTP request with the Python script payload, then verify the response.. RESTCONF operations require authentication, correct URL, headers, and payload; verify with response.

Answer

Construct the RESTCONF URL and headers, then authenticate to the device, then send the HTTP request with the Python script payload, then verify the response.

Answer

Send the HTTP request with the Python script payload, then construct the RESTCONF URL and headers, then authenticate to the device, then verify the response.

Answer

Authenticate to the device, then send the HTTP request with the Python script payload, then construct the RESTCONF URL and headers, then verify the response.

Question 5

A Cisco DevNet engineer is configuring model-driven telemetry on a Cisco IOS-XE device. The telemetry subscription includes the following path: 'Cisco-IOS-XE-native:native/interface/GigabitEthernet[Name='1/0/1']/ip/address'. Which part of this path identifies a specific list instance?

Accepted Answer

[Name='1/0/1']. The XPath expression `[Name='1/0/1']` is a predicate filter that selects a specific list instance from the `GigabitEthernet` YANG list. In YANG model-driven telemetry, list keys are used to identify individual entries, and the predicate syntax `[key='value']` pinpoints exactly one instance within the list.

Answer

Cisco-IOS-XE-native

Answer

GigabitEthernet

Answer

ip/address

Question 6

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 7

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

Accepted Answer

Use version control for all automation scripts and playbooks. 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 8

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 9

A network automation script using Ansible with the cisco.ios.ios_config module fails with "Unsupported parameters for (cisco.ios.ios_config) module: src." What is the most likely issue?

Accepted Answer

The module does not support 'src' parameter; it should use 'lines'. The error message 'Unsupported parameters for (cisco.ios.ios_config) module: src' indicates that the 'src' parameter is not a valid parameter for the cisco.ios.ios_config module. In Ansible, the correct parameter to specify configuration lines directly is 'lines', not 'src'. The 'src' parameter is used by other modules like ios_config (from the older ansible.netcommon collection) or for file-based configuration, but the cisco.ios.ios_config module expects configuration content via 'lines' or 'parents'.

Answer

The Ansible version is too old

Answer

The inventory file has incorrect credentials

Answer

The network device is unreachable

Question 10

Match each HTTP method to its typical use case in REST APIs.

Accepted Answer

GET: Retrieve a resource. Standard RESTful HTTP methods: GET retrieves, POST creates, PUT replaces, DELETE removes. Common confusions swap GET with POST or misuse PUT for partial updates (which is PATCH).

Answer

GET: Create a new resource

Answer

POST: Retrieve a resource

Question 11

A developer needs to use Postman to test an API that uses Basic authentication. How should the credentials be configured in Postman?

Accepted Answer

Use the Authorization tab, select Basic Auth, and enter username and password. Postman's Authorization tab provides a Basic Auth type that automatically encodes credentials. The raw base64-encoded string is the underlying mechanism but is handled by Postman. Basic auth does not use bearer tokens.

Answer

Send the credentials in the request body as JSON

Answer

Set the Authorization header to 'Bearer base64(username:password)'

Answer

Add a query parameter 'auth' with base64-encoded credentials

Question 12

Refer to the exhibit. A developer executes this Python script against a Cisco device. Assuming valid credentials and network connectivity, what is printed to the console?

Accepted Answer

The running configuration of the device in XML format. The script uses the `ncclient` library to connect to a Cisco device via NETCONF, which defaults to retrieving the running configuration. The `get_config(source='running')` method fetches the running configuration in XML format, so the output printed to the console is the running configuration in XML. Option C is correct because the code explicitly requests the running configuration.

Answer

An exception due to invalid credentials

Answer

The startup configuration of the device in XML format

Answer

A JSON representation of the device interfaces

Question 13

A developer is creating a Helm chart for a stateless web application. Where should the application's configuration settings (like log level and feature flags) be stored?

Accepted Answer

In values.yaml file of the Helm chart.. In a Helm chart, the `values.yaml` file is the standard location for configuration settings like log level and feature flags. This file allows developers to externalize configuration from the application code and Docker image, enabling environment-specific overrides without rebuilding the image. Helm uses `values.yaml` to inject these settings into Kubernetes manifests via template directives, making the chart reusable across different deployments.

Answer

Directly in the Docker image.

Answer

Hardcoded in the application code.

Answer

In a Kubernetes Secret.

Question 14

A network engineer runs the Ansible playbook shown in the exhibit, but it fails. The error indicates the module 'cisco.ios.ios_vlan' does not exist. What is the most likely cause?

Accepted Answer

The module name is misspelled; it should be 'ios_vlans'. The error indicates that the module 'cisco.ios.ios_vlan' does not exist. In the cisco.ios collection, the correct module name for managing VLANs is 'ios_vlans' (plural), not 'ios_vlan'. This is a common naming mistake because many other Ansible modules use singular names, but the ios_vlan module was deprecated and replaced by ios_vlans in newer versions of the collection.

Answer

The collection 'cisco.ios' is not installed

Answer

The 'state: present' is invalid for this module

Answer

The playbook lacks 'become: yes'

Question 15

What does a TTL of 128 indicate about the destination host?

Accepted Answer

It is a Windows host. The Time-to-Live (TTL) value in an IP packet is decremented by each router that forwards the packet. When a host receives a packet, the remaining TTL value can indicate the operating system of the source that sent it. Windows operating systems typically set the initial TTL to 128, so a TTL of 128 in a received packet strongly suggests the destination host (the sender of that packet) is a Windows host.

Answer

It is a network switch

Answer

It is a Cisco router

Answer

It is a Linux host

Question 16

A developer writes a Python script to read a configuration file. Which code snippet correctly opens the file 'config.json' for reading and ensures the file is closed after use?

Accepted Answer

with open('config.json', 'r') as f:
    data = f.read(). It uses the `with` statement, which is a context manager that automatically calls `f.close()` when the block exits, ensuring the file is properly closed even if an exception occurs. The `'r'` mode opens the file for reading, and `f.read()` reads the entire contents into the `data` variable.

Answer

open('config.json', 'r') as f:
    data = f.read()

Answer

with open('config.json', 'r') as f, data = f.read()

Answer

file = open('config.json', 'r')
data = file.read()
file.close()

Question 17

Which TWO of the following are best practices when using REST APIs in Cisco networking environments?

Accepted Answer

Always handle HTTP error codes like 4xx and 5xx.. Handling HTTP error codes like 4xx (client errors) and 5xx (server errors) is essential for robust REST API integration. In Cisco environments, APIs such as those for DNA Center or Meraki return these codes to indicate issues like authentication failure (401), rate limiting (429), or server overload (503). Proper error handling allows the application to retry, log, or alert appropriately, preventing silent failures and ensuring reliable network automation.

Answer

Send credentials as plain text in every request.

Answer

Poll the API every second to get real-time updates.

Answer

Embed API keys directly in the URL query parameters.

Question 18

A developer is writing a Python script to interact with a Cisco device using RESTCONF. The script sends a PUT request to modify an interface configuration. Which HTTP response code indicates that the resource was successfully created?

Accepted Answer

201 Created. In RESTCONF, a successful PUT request that creates a new resource returns HTTP 201 Created. This aligns with RFC 8040, where PUT can be used for both creation and replacement; the 201 response specifically indicates the resource did not exist before and was created by the request.

Answer

404 Not Found

Answer

200 OK

Answer

204 No Content

Question 19

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. 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

Question 20

A network administrator automates the provisioning of Meraki MX security appliances using the Meraki Dashboard API. The Python script reads a CSV file with site details and creates VLANs, firewall rules, and VPN settings. Recently, the script started throwing an HTTP 429 error. The script is single-threaded and makes fewer than 10 requests per second. Which of the following is the most likely cause of the 429 error?

Accepted Answer

The organization has a lower rate limit than the API key's default.. The HTTP 429 (Too Many Requests) error indicates the client has exceeded the rate limit imposed by the Meraki Dashboard API. Even though the script makes fewer than 10 requests per second, the organization-level rate limit can be lower than the default API key limit. Option D is correct because the organization's rate limit overrides the default, and the script's request rate may still exceed that lower threshold.

Answer

The API key has been revoked.

Answer

The rate limit for the API key is 5 requests per second.

Answer

The Meraki cloud is under maintenance.