200-901 Practice Exam 51 — 20 Questions

Question 1

A developer is building an application that interacts with the Webex API to create rooms and send messages. The application needs to receive real-time notifications when a new message is posted in any room. Which TWO actions should the developer take? (Choose two.)

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

Accepted Answer

Provide a target URL where the webhook sends the notification. Option B is correct because Webex webhooks require the developer to supply a targetUrl — an HTTPS endpoint on their own publicly reachable service — where Webex will POST the notification payload when the subscribed event fires. Option D is correct because real-time notification of a new message is delivered by registering a webhook whose event is 'created' and whose resource is 'messages' (i.e., message.created), which is exactly the trigger Webex uses for newly posted messages. Option A is wrong because polling GET /v1/messages every second is inefficient, rate-limit prone, and not a real-time push mechanism. Option C is wrong because roomId is a filter/query parameter for listing messages, not a mechanism for receiving notifications. Option E is wrong because 'seen' is not a valid message event for this purpose and the payload described does not register a message-created subscription.

Answer

Poll the GET /v1/messages endpoint every second

Answer

Use the 'roomId' parameter to filter messages

Answer

Send a POST request to /v1/webhooks with 'resource: messages' and 'event: seen'

Question 2

Which TWO statements about the MVC pattern are correct? (Choose two.)

Accepted Answer

Controller handles user input and updates the Model.. Option B is correct because in MVC the Controller is the component that receives and interprets user input (e.g., HTTP requests or UI events) and then invokes the appropriate operations on the Model to change application state. Option C is correct because the View is responsible for rendering/presenting the Model's data to the user, typically reading from the Model (or a ViewModel) without containing business logic. Option A is incorrect because the Model must not depend on the View; dependencies flow from View/Controller toward the Model, not the reverse. Option D is incorrect because the Model represents application data and business rules, not the user interface. Option E is incorrect because the View should not directly modify the Model; modifications go through the Controller to preserve separation of concerns.

Answer

Model is dependent on the View.

Answer

Model represents the user interface.

Answer

View directly modifies the Model.

Question 3

Which THREE of the following are characteristics of GraphQL compared to REST? (Choose three.)

Accepted Answer

Typically uses a single endpoint.. Option A is correct because GraphQL exposes a single endpoint (commonly /graphql) through which all queries and mutations are sent, unlike REST's resource-specific URLs. Option B is correct because GraphQL APIs are defined by a strongly typed schema using the Schema Definition Language, specifying types, fields, and operations that enable validation and introspection. Option C is correct because GraphQL clients send queries declaring precisely the fields they need, so the server returns exactly that shape of data. Option D is not a GraphQL characteristic; over-fetching is a well-known REST problem that GraphQL is designed to avoid. Option E describes REST, where distinct endpoints map to different resources, whereas GraphQL uses one endpoint.

Answer

Over-fetching of data is common.

Answer

Multiple endpoints for different resources.

Question 4

Which TWO of the following are essential steps in a typical Git workflow when collaborating on a feature branch? (Choose two.)

Accepted Answer

Merge the branch into master. Option E (Create a branch) is essential because a feature branch isolates new work from the mainline, allowing commits to be made without affecting master until the work is ready. Option B (Merge the branch into master) is essential because the completed feature must be integrated back into the mainline so other collaborators can build on it. Option A (Rebase onto master) is a valid but optional technique for updating or linearizing history, not a required step in every workflow. Option C (Delete the remote repository) is destructive and unrelated to normal collaboration. Option D (Stash changes before switching branches) is only a convenience when the working tree is dirty, not an essential step of the workflow.

Answer

Rebase onto master

Answer

Delete the remote repository

Answer

Stash changes before switching branches

Question 5

A developer is implementing error handling in a script that makes multiple API calls to Cisco ACI. Which approach is best practice for handling transient network failures?

Accepted Answer

Retry with exponential backoff. Exponential backoff is the best practice for handling transient network failures in API calls because it reduces server load and prevents thundering herd problems. Cisco ACI's REST API can become overwhelmed if many clients retry simultaneously with fixed delays, making exponential backoff the recommended approach in REST API design and Cisco's own documentation.

Answer

Retry with fixed delay

Answer

Ignore errors and continue

Answer

Always retry immediately

Question 6

A DevOps team uses a CI/CD pipeline to deploy network configurations. They want to ensure that only authorized network engineers can trigger changes to production devices. Which integration is most appropriate?

Accepted Answer

Implement Role-Based Access Control (RBAC) on the CI/CD tool. Role-Based Access Control (RBAC) on the CI/CD tool directly restricts which users or groups can trigger pipeline jobs that modify production network devices. This ensures that only authorized network engineers have the permissions to execute changes, aligning with the principle of least privilege in deployment pipelines.

Answer

Encrypt the Ansible vault password

Answer

Use a separate staging environment

Answer

Use a pre-commit hook in Git to validate YAML syntax

Question 7

Which TWO of the following are functions of the transport layer in the OSI model? (Choose two.)

Accepted Answer

Segmentation and reassembly of data.. Segmentation and reassembly of data is a core function of the transport layer. The transport layer (e.g., TCP) takes data from the session layer, breaks it into smaller segments (segmentation), assigns sequence numbers, and then reassembles these segments in the correct order at the destination. This allows large data streams to be transmitted efficiently over the network layer, which has a maximum transmission unit (MTU) size.

Answer

Adding a trailer for error detection.

Answer

Encrypting data for secure transmission.

Answer

Determining the best path to a destination.

Question 8

A developer is using the Meraki Dashboard API to list all networks in an organization. The response includes a Link header with rel="next". What does this indicate?

Accepted Answer

There are additional data pages to retrieve.. Meraki uses Link headers for pagination; the next link indicates there are more pages of results to fetch.

Answer

The organization ID is invalid.

Answer

The API version is deprecated and should be updated.

Answer

The request is rate-limited and needs to wait.

Question 9

In Python, which keyword is used to define a function that does not return any value?

Accepted Answer

def. In Python, the `def` keyword is used to define any function, regardless of whether it returns a value. A function that does not explicitly return a value automatically returns `None`. The `def` keyword is the correct answer because it is the fundamental syntax for function definition, and the question asks for the keyword used to define the function itself, not the mechanism for returning or omitting a value.

Answer

pass

Answer

yield

Answer

return

Question 10

In Python, which of the following is a valid way to define a function that accepts a variable number of positional arguments?

Accepted Answer

def func(*args):. In Python, the `*args` syntax in a function definition allows the function to accept a variable number of positional arguments. The asterisk (`*`) collects all extra positional arguments into a tuple named `args`, enabling flexible argument handling.

Answer

def func(args):

Answer

def func(args*):

Answer

def func(**kwargs):

Question 11

Which TWO statements correctly describe differences between model-driven telemetry and traditional SNMP polling?

Accepted Answer

Model-driven telemetry reduces device CPU usage compared to frequent SNMP polling. Model-driven telemetry uses a push model that sends data only when there is a change or at a configured interval, which significantly reduces the device CPU overhead compared to frequent SNMP polling, where the device must process and respond to each individual GET request from the NMS. This efficiency gain is a primary advantage of telemetry over traditional polling.

Answer

SNMP supports push-based notifications using informs

Answer

Model-driven telemetry can only be used with NETCONF

Answer

SNMP uses YANG models for data definition

Question 12

An engineer is using the Cisco Meraki Dashboard API to retrieve a list of all network clients for a specific network. Which TWO of the following are required to successfully make this API call?

Accepted Answer

Network ID in the URL path. The Meraki Dashboard API endpoint for listing network clients (GET /networks/{networkId}/clients) requires the network ID as a path parameter to identify the specific network from which to retrieve client data. Without the network ID in the URL, the API cannot determine which network's clients to return, making it a mandatory component of the request.

Answer

Bearer token in the Authorization header

Answer

Organization ID in the URL path

Answer

API key as a query parameter

Question 13

A developer is designing a data model for network device configurations using YANG. They need to represent a list of interfaces where each interface has a name (string) and speed (enumeration). Which YANG statement correctly defines this structure?

Accepted Answer

list interface { key name; leaf name { type string; } leaf speed { type enumeration; } }. YANG requires a `list` statement to define a collection of entries with multiple leafs, and a `key` statement to uniquely identify each list entry. The `list interface` with `key name` allows multiple interfaces, each having both a `name` (string) and `speed` (enumeration), matching the requirement exactly.

Answer

leaf interface-list { type string; }

Answer

leaf-list interface { type string; }

Answer

list interface { leaf name { type string; } leaf speed { type enumeration; } }

Question 14

Refer to the exhibit. Which Cisco DNA Center Intent API request produced this response?

Accepted Answer

GET /dna/intent/api/v1/network-device/{id}. The response shows detailed information for a single network device, including its management IP address, platform ID, and serial number. The GET /dna/intent/api/v1/network-device/{id} request retrieves details for a specific device identified by its unique ID, which matches the granular, single-device data in the exhibit. This is the correct Intent API endpoint for fetching a device by ID.

Answer

GET /dna/intent/api/v1/network-device

Answer

POST /dna/intent/api/v1/network-device

Answer

PUT /dna/intent/api/v1/network-device/{id}

Question 15

Which Git command is used to create a new branch and switch to it in one step?

Accepted Answer

git checkout -b . The 'git checkout -b ' command creates a new branch and switches to it immediately.

Answer

git branch <branch>

Answer

git branch -d

Answer

git checkout

Question 16

Which THREE of the following are characteristics of HTTP/2 compared to HTTP/1.1?

Accepted Answer

Header compression using HPACK. HPACK compression reduces header overhead by encoding header fields, which is a key improvement over HTTP/1.1's uncompressed headers. This minimizes latency and bandwidth usage, especially for repeated headers like cookies and user-agent.

Answer

Plaintext headers for debugging

Answer

Requires multiple TCP connections for parallel requests

Question 17

In a Python script using the 'requests' library to interact with Cisco DNA Center API, which function call is used to send a POST request with JSON data?

Accepted Answer

requests.post(url, json=data). The `requests.post()` function is specifically designed to send HTTP POST requests, and passing the `json=data` parameter automatically serializes the Python dictionary to JSON and sets the `Content-Type` header to `application/json`. This is the standard way to create a resource via Cisco DNA Center's REST API endpoints that expect JSON payloads.

Answer

requests.patch(url, json=data)

Answer

requests.get(url, json=data)

Answer

requests.put(url, json=data)

Question 18

A Python script uses the 'requests' library to make a POST request to create a new resource. Which HTTP status code indicates successful creation?

Accepted Answer

201 Created. According to the REST API conventions, a successful POST request returns status code 201 Created.

Answer

204 No Content

Answer

200 OK

Answer

301 Moved Permanently

Question 19

Which THREE of the following are benefits of using event-driven architecture in a distributed system? (Choose three.)

Accepted Answer

Loose coupling between services. Option A is correct because in event-driven architecture producers emit events without knowing which consumers will handle them, so services interact only through the event channel rather than direct API calls, achieving loose coupling. Option B is correct because events are published and consumed as they occur, enabling real-time data processing and immediate reaction to state changes rather than relying on periodic polling or batch jobs. Option C is correct because each consumer or event processor can be scaled independently and events can be distributed across multiple partitions or instances, providing scalability through independent processing. Option D is not correct because event-driven systems typically depend on message brokers or event streaming platforms such as Kafka, RabbitMQ, or Amazon SNS/SQS to route, buffer, and deliver events. Option E is not correct because event-driven communication is inherently asynchronous, and debugging is generally more complex due to distributed tracing, eventual consistency, and the need to correlate events across services.

Answer

Eliminates the need for message brokers

Answer

Simpler debugging due to synchronous communication

Question 20

Refer to the exhibit. A developer is trying to access the REST API on a Cisco IOS XE device but receives a 401 Unauthorized error. What is the most likely cause?

Accepted Answer

Authentication requires local credentials, but none were provided. A 401 Unauthorized error specifically indicates that authentication is required but was either missing or invalid. For Cisco IOS XE REST API access, the device requires local credentials (username and password) to be provided in the request, typically via HTTP Basic Authentication. Without these credentials, the server rejects the request with a 401 status.

Answer

The device does not support REST API

Answer

HTTPS is not configured

Answer

HTTP server is not enabled