200-901 Exam Simulation — 95 Questions

Question 1

Refer to the exhibit. A developer is building a Docker image for a Node.js application. The Dockerfile contains:
```
FROM node:14
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
CMD ["node", "app.js"]
```
When building, the error shown occurs. What is the most likely cause?

Accepted Answer

The application is running as a non-root user (e.g., node) that lacks write permission to the working directory.. The error occurs because the official Node.js Docker image (node:14) runs as a non-root user named 'node' by default. The WORKDIR /usr/src/app is owned by root, so the 'node' user lacks write permission to that directory. When npm install tries to create node_modules or write package-lock.json, it fails with a permission error. Option D correctly identifies this user-permission mismatch.

Answer

The Dockerfile should use the root user for running npm install.

Answer

The npm install command should be run with the --unsafe-perm flag.

Answer

The base image node:14 is outdated and contains a bug.

Question 2

A network engineer is configuring EtherChannel between two switches. The switches are connected via four links. The engineer wants to load balance traffic based on source and destination IP addresses. Which configuration command should be used on Cisco IOS?

Accepted Answer

port-channel load-balance src-dst-ip. The command 'port-channel load-balance src-dst-ip' configures EtherChannel to use both the source and destination IP addresses in the hash algorithm, which is exactly what the engineer needs for load balancing based on source and destination IP addresses. This ensures traffic distribution across the four links by computing a hash on the combination of source and destination IPs, providing a balanced distribution for IP traffic.

Answer

port-channel load-balance src-ip

Answer

port-channel load-balance dst-ip

Answer

port-channel load-balance src-dst-mac

Question 3

A developer is using the Meraki Dashboard API to retrieve a list of clients for a network. The API returns a 429 error. What should the developer do to handle this correctly?

Accepted Answer

Wait for the number of seconds specified in the Retry-After header before retrying.. A 429 HTTP status code indicates 'Too Many Requests,' meaning the client has exceeded the rate limit imposed by the Meraki Dashboard API. The correct handling is to respect the Retry-After header, which specifies the number of seconds the client must wait before retrying the request, as per RFC 7231 Section 7.1.3. This ensures compliance with API rate limits and prevents further throttling or temporary blocking.

Answer

Ignore the error and continue, as 429 is a temporary issue.

Answer

Switch to a different base URL to bypass the limit.

Answer

Increase the request rate by using multiple API keys in parallel.

Question 4

Which two authentication methods are commonly used with Cisco APIs? (Choose two.)

Accepted Answer

Basic Authentication over HTTPS. Basic Authentication over HTTPS is commonly used with Cisco APIs because it sends a base64-encoded username:password pair in the Authorization header, which is a simple and widely supported method for authenticating REST API requests. Cisco's REST APIs, such as those on DNA Center and Meraki, often accept Basic Auth as a fallback or for legacy integration, though it is less secure than token-based methods.

Answer

SNMPv3

Answer

SSH Key

Answer

RADIUS

Question 5

Which THREE are valid ways to expose ConfigMap data to a pod in Kubernetes?

Accepted Answer

As environment variables. Kubernetes allows ConfigMap data to be exposed as environment variables inside a pod using the `env` or `envFrom` field in the pod spec. This is a common method for injecting configuration into containers without modifying the container image.

Answer

As a Kubernetes Secret

Answer

As a container image label

Question 6

A company uses a blue/green deployment strategy for their web application. The current live version is blue, and a new version green is ready. The load balancer currently routes all traffic to blue. What is the correct next step to switch traffic to green with minimal downtime?

Accepted Answer

Update the load balancer to route all traffic to green. In a blue/green deployment, the entire new version (green) is deployed alongside the current live version (blue). The correct next step to switch traffic with minimal downtime is to update the load balancer to route all traffic to green. This instant switch avoids the incremental risk of rolling updates and ensures a clean cutover that can be quickly reverted if issues arise.

Answer

Scale down blue pods and scale up green

Answer

Perform a rolling update from blue to green

Answer

Delete the blue deployment and create green

Question 7

A developer is working with the Cisco SD-WAN vManage API to monitor overlay tunnels. They need to retrieve a list of all devices with their site IDs and IP addresses. Which API endpoint is most appropriate?

Accepted Answer

GET /dataservice/device. The GET /dataservice/device endpoint returns a list of all devices managed by the Cisco SD-WAN vManage, including their site IDs and IP addresses. This is the correct endpoint for retrieving device inventory details, as it provides the necessary fields like 'deviceId', 'system-ip', and 'site-id' in the response.

Answer

GET /dataservice/device/monitor

Answer

GET /dataservice/device/device

Answer

GET /dataservice/device/overlay

Question 8

An engineer is exploring YANG models for network interfaces. They need a vendor-neutral model that can be used across multiple device types. Which YANG model should they use?

Accepted Answer

OpenConfig interfaces. OpenConfig models are vendor-neutral, while Cisco native models are vendor-specific.

Answer

ietf-interfaces

Answer

Cisco-NX-OS-device

Answer

Cisco-IOS-XE-native

Question 9

A developer is using the Meraki API to retrieve a list of networks for an organization. Which HTTP method and endpoint should be used?

Accepted Answer

GET /organizations/{organizationId}/networks. The Meraki API uses RESTful conventions where retrieving a list of resources is done with a GET request. The endpoint GET /organizations/{organizationId}/networks returns all networks belonging to a specific organization, as documented in the Meraki API reference. This matches the standard pattern for listing child resources under a parent resource.

Answer

POST /organizations/{organizationId}/networks

Answer

GET /networks

Answer

PUT /organizations/{organizationId}/networks

Question 10

A developer notices that after a new deployment, the application is not receiving traffic. The Service selector does not match the pod labels. Which kubectl command can be used to inspect the Service's selector?

Accepted Answer

kubectl describe service my-service. The `kubectl describe service my-service` command displays detailed information about the Service, including its selector field, which defines the label key-value pairs used to match pods. This allows the developer to directly compare the selector against the pod labels to identify the mismatch. It is the most straightforward way to inspect the selector without needing to parse raw YAML or execute commands inside the service.

Answer

kubectl exec service/my-service -- cat /etc/hosts

Answer

kubectl get service my-service -o yaml

Answer

kubectl logs service/my-service

Question 11

A network engineer is troubleshooting connectivity issues and wants to verify the path that packets take from a source to a destination IP address. Which OSI layer is primarily responsible for packet forwarding and routing?

Accepted Answer

Layer 3 - Network. The Network layer (Layer 3) is responsible for packet forwarding and routing, using logical IP addresses to determine the best path from source to destination. Protocols like IP (IPv4/IPv6) and routing protocols (e.g., OSPF, BGP) operate at this layer to make forwarding decisions. The traceroute command is a common tool that leverages Layer 3 TTL (Time-to-Live) fields to map the path packets take.

Answer

Layer 4 - Transport

Answer

Layer 1 - Physical

Answer

Layer 2 - Data Link

Question 12

A DevOps engineer is managing a Git repository and wants to discard local changes to a file and revert it to the last committed state. Which TWO commands can accomplish this? (Choose two.)

Accepted Answer

git checkout -- . Both `git checkout -- ` and `git restore ` discard unstaged local changes to a file, reverting it to the content of the last commit (HEAD). `git checkout -- ` is the traditional command, while `git restore ` is the newer, more intuitive alternative introduced in Git 2.23. Both operate on the working tree without affecting the staging area or commit history.

Answer

git reset --hard HEAD

Answer

git stash drop

Answer

git revert <file>

Question 13

A developer needs to send a message to a specific room in Webex using the API. What is the correct endpoint and required body parameter for the room destination?

Accepted Answer

POST /v1/messages with roomId parameter. To send a message to a Webex room, use POST /v1/messages with the roomId parameter to specify the target room.

Answer

POST /v1/messages with toPersonEmail parameter

Answer

POST /v1/memberships with roomId

Answer

POST /v1/rooms with message text

Question 14

Match each HTTP status code to its meaning.

Accepted Answer

200 OK: Request succeeded.. The correct matches are: 200 OK = Request succeeded, 201 Created = Resource created successfully, 400 Bad Request = Malformed syntax or invalid request, 404 Not Found = Resource not found. Common confusions include swapping 200 and 201, as well as 400 and 404.

Answer

200 OK: Resource created.

Answer

404 Not Found: Bad request.

Question 15

In software architecture, which pattern separates an application into three interconnected components: Model (data), View (UI), and Controller (input logic)?

Accepted Answer

MVC (Model-View-Controller). The MVC pattern explicitly separates an application into three interconnected components: Model (data and business logic), View (user interface), and Controller (handles user input and updates the Model/View). This is the foundational architectural pattern for many web frameworks like Django, Ruby on Rails, and Spring MVC, where the Controller receives HTTP requests, interacts with the Model, and selects the appropriate View for rendering.

Answer

Microservices

Answer

Event-driven

Answer

REST

Question 16

A Kubernetes cluster runs a microservice that needs to read configuration values from a ConfigMap and sensitive database credentials from a Secret. The pod manifest references both resources. How should the Secret be mounted to avoid exposing sensitive data in logs or environment variables?

Accepted Answer

Using a volume mount with a secret volume. Mounting a Secret as a volume stores the data in the tmpfs (RAM-backed filesystem) of the pod, which is not written to disk and is not exposed via environment variables that could be logged or printed by the application. This approach prevents accidental leakage of sensitive data through log outputs or environment variable dumps, as the application must explicitly read the file from the mount point.

Answer

Hardcoding the credentials in the ConfigMap

Answer

Using a sidecar container to fetch secrets via API

Answer

Using envFrom with secretRef

Question 17

In a network automation workflow, a developer needs to ensure idempotency. What does idempotency mean in this context?

Accepted Answer

Running the script once produces the same result as running it multiple times. Idempotency in network automation means that executing an operation multiple times results in the same network state as executing it once. For example, using a REST API PUT request to set a VLAN configuration will leave the device in the same state whether the request is sent once or repeatedly, because PUT is inherently idempotent. This prevents unintended side effects like duplicate VLANs or interface misconfigurations when a script is retried due to network failures or timeouts.

Answer

The script uses a single API call

Answer

The script can recover from failures

Answer

The script can run on multiple devices simultaneously

Question 18

A developer needs to create a Python function that accepts any number of keyword arguments and prints them. Which function definition correctly uses **kwargs?

Accepted Answer

def print_args(**kwargs): print(kwargs). The **kwargs syntax in a Python function definition collects any number of keyword arguments into a dictionary. The function then prints that dictionary, which matches the requirement to accept and print any number of keyword arguments.

Answer

def print_args(*args): print(args)

Answer

def print_args(kwargs): print(kwargs)

Answer

def print_args(*kwargs): print(kwargs)

Question 19

A network engineer configures an HTTP/2 server. Which feature of HTTP/2 reduces overhead by compressing headers using HPACK?

Accepted Answer

HPACK. HPACK is the header compression mechanism specified for HTTP/2 (RFC 7541). It reduces overhead by encoding HTTP headers into a compact binary format using static and dynamic tables, eliminating redundant header data across requests. This directly addresses the question's focus on reducing overhead through header compression.

Answer

Server push

Answer

Binary framing layer

Answer

Multiplexed streams

Question 20

An application developer is using a protocol that does not require a connection setup and has minimal header overhead. Which transport protocol is being used?

Accepted Answer

UDP. UDP (User Datagram Protocol) is a connectionless transport-layer protocol that does not require a handshake (no SYN/SYN-ACK/ACK) and has minimal header overhead (only 8 bytes, compared to TCP's 20 bytes). This makes it ideal for applications like DNS queries, streaming media, or real-time communications where low latency is more critical than guaranteed delivery.

Answer

TCP

Answer

HTTP

Answer

ICMP