200-901 Software Development and Design — 40 Questions

Question 1

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(). Option A is correct because 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 2

A network automation script uses the requests library to retrieve device information from a REST API. The API requires authentication via a bearer token. Which code example correctly sets the Authorization header?

Accepted Answer

headers = {'Authorization': 'Bearer ' + token}
response = requests.get(url, headers=headers). Option C is correct because it constructs the Authorization header using the 'Bearer' scheme, which is the standard method for passing OAuth 2.0 bearer tokens in HTTP requests. The requests library requires the header to be explicitly set as a dictionary, and the token must be prefixed with 'Bearer ' to comply with RFC 6750.

Answer

headers = {'Authorization': 'Token ' + token}
response = requests.get(url, headers=headers)

Answer

response = requests.get(url, headers={'Authorization': token})

Answer

response = requests.get(url, auth=('Bearer', token))

Question 3

A developer is using Git for version control. After creating a new feature branch 'feature-login' from 'main', they make several commits. Meanwhile, another developer has merged changes into 'main'. The developer wants to incorporate the latest main changes into 'feature-login' without creating a merge commit. Which Git command should they use?

Accepted Answer

git pull --rebase origin main. Option C is correct because `git pull --rebase origin main` fetches the latest changes from the remote `main` branch and then rebases the current `feature-login` branch onto those changes. This incorporates the new commits from `main` without creating a merge commit, resulting in a linear history. The `--rebase` flag ensures that the developer's commits are replayed on top of the updated `main`, avoiding the extra merge commit that `git merge` would create.

Answer

git rebase main

Answer

git merge main

Answer

git checkout main && git pull && git checkout feature-login && git merge main

Question 4

Which HTTP status code indicates that a POST request successfully created a new resource?

Accepted Answer

201 Created. HTTP 201 Created is the standard response for a successful POST that creates a resource.

Answer

204 No Content

Answer

301 Moved Permanently

Answer

200 OK

Question 5

In Python, which data type is used to represent an unordered collection of unique elements?

Accepted Answer

set. In Python, a set is the correct data type for representing an unordered collection of unique elements. Sets automatically enforce uniqueness by using a hash table internally, so duplicate values are ignored upon insertion. This makes them ideal for operations like membership testing and deduplication, where order is irrelevant.

Answer

tuple

Answer

list

Answer

dict

Question 6

A Python function needs to accept a variable number of keyword arguments. Which parameter syntax should be used?

Accepted Answer

**kwargs. In Python, the **kwargs syntax allows a function to accept a variable number of keyword arguments by collecting them into a dictionary. This is the correct parameter syntax for handling arbitrary keyword arguments, as specified in Python's function definition rules.

Answer

*kwargs

Answer

*args

Answer

&kwargs

Question 7

In a microservices architecture, which of the following is a key characteristic compared to a monolithic architecture?

Accepted Answer

Services communicate via lightweight protocols such as HTTP/REST.. Microservices are independently deployable, scalable, and developed by small teams, whereas a monolith is a single deployable unit.

Answer

Changes require rebuilding the entire application.

Answer

The entire application is deployed as a single unit.

Answer

All services share the same database.

Question 8

Which Python list comprehension correctly creates a list of squares for even numbers from 0 to 10?

Accepted Answer

[x**2 for x in range(11) if x % 2 == 0]. Option A is correct because it uses list comprehension syntax with `x**2` to square each number, iterates over `range(11)` to include numbers 0 through 10, and applies the condition `if x % 2 == 0` to filter only even numbers. This produces the list `[0, 4, 16, 36, 64, 100]` as required.

Answer

[x*2 for x in range(11) if x % 2 == 0]

Answer

[x**2 for x in range(10) if x % 2]

Answer

[x**2 for x in range(10) if x % 2 == 0]

Question 9

A developer needs to parse a JSON string received from a REST API into a Python dictionary. Which function should they use?

Accepted Answer

json.loads(). json.loads() converts a JSON string into a Python object (dict, list, etc.).

Answer

json.dumps()

Answer

json.load()

Answer

json.dump()

Question 10

In the MVC (Model-View-Controller) pattern, which component is responsible for handling user input and updating the model?

Accepted Answer

Controller. In the MVC pattern, the Controller is the component that receives user input (e.g., HTTP requests, button clicks) and translates it into commands that update the Model. It acts as the intermediary between the View and the Model, ensuring that user actions trigger appropriate changes in the application's data layer.

Answer

Model

Answer

Router

Answer

View

Question 11

What does the Git command 'git log --oneline' display?

Accepted Answer

A summary of each commit on one line. The --oneline flag condenses each commit to a single line showing the commit hash and message.

Answer

A list of files changed in the last commit

Answer

The branches and their latest commits

Answer

The differences between the working directory and the last commit

Question 12

A Python script sends a PUT request to update a resource. The API returns a response with status code 204. What does this indicate?

Accepted Answer

The update was successful and no content is returned.. 204 No Content means the request succeeded, but there is no response body (common for PUT or DELETE).

Answer

The request was malformed.

Answer

The resource was not found.

Answer

The update failed due to a server error.

Question 13

Which TWO of the following are valid branching strategies in Git? (Choose two.)

Accepted Answer

Feature branching. Feature branching (C) is a valid Git branching strategy where each new feature is developed in its own branch, allowing isolated work without disrupting the main codebase. GitFlow (E) is another valid strategy that defines a strict branching model with master, develop, feature, release, and hotfix branches, commonly used for projects with scheduled releases.

Answer

Rebase-only

Answer

Merge avoidance

Answer

Direct commit to main

Question 14

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

Accepted Answer

Loose coupling between services. Event-driven architecture promotes loose coupling, scalability, and real-time responsiveness.

Answer

Eliminates the need for message brokers

Answer

Simpler debugging due to synchronous communication

Question 15

Which TWO of the following Python exception handling statements are valid? (Choose two.)

Accepted Answer

try:
    x = 1/0
except ZeroDivisionError as e:
    print(e). Option A is correct because Python's `except` clause uses the `as` keyword to bind the exception instance to a variable, allowing access to the error message via `e`. This syntax is valid and commonly used for logging or inspecting exception details.

Answer

try:
    x = 1/0
except ZeroDivisionError, e:
    print(e)

Question 16

A developer is writing a Python script to iterate over a list of server hostnames. Which loop structure is most appropriate to process each hostname in the list?

Accepted Answer

for hostname in hostnames: print(hostname). The 'for item in list' loop iterates directly over each element, making it the simplest and most readable for processing each hostname.

Answer

for i, hostname in enumerate(hostnames): print(hostname)

Answer

while len(hostnames) > 0: print(hostnames.pop())

Answer

for i in range(len(hostnames)): print(hostnames[i])

Question 17

A Python script uses a dictionary to store device configuration parameters. Which key, if any, will raise a KeyError if it does not exist in the dictionary?

Accepted Answer

config['timeout']. Option B is correct because using square bracket notation (config['timeout']) on a dictionary will raise a KeyError if the specified key does not exist. This is a fundamental behavior of Python dictionaries: direct key access without a fallback mechanism throws an exception when the key is missing.

Answer

config.setdefault('timeout', 30)

Answer

config.get('timeout')

Answer

config.pop('timeout', None)

Question 18

When using the requests library in Python to send a POST request, which parameter should be used to send a JSON payload in the request body?

Accepted Answer

json=payload. The json= parameter automatically serializes the Python dictionary to JSON and sets the Content-Type header to application/json.

Answer

params=payload

Answer

files=payload

Answer

data=json.dumps(payload)

Question 19

A network engineer writes a Python script to handle exceptions when making REST API calls. Which exception type should be caught to handle network connectivity issues (e.g., DNS failure, refused connection)?

Accepted Answer

requests.exceptions.ConnectionError. Option B is correct because `requests.exceptions.ConnectionError` is specifically raised when the underlying TCP connection fails, which includes scenarios like DNS resolution failures, refused connections, or the remote host being unreachable. This exception is a subclass of `RequestException` and directly maps to network-level issues at the transport layer, making it the precise exception to catch for connectivity problems.

Answer

requests.exceptions.RequestException

Answer

requests.exceptions.HTTPError

Answer

requests.exceptions.Timeout

Question 20

Given the following Python code snippet:

with open('config.json', 'r') as f:
    data = json.load(f)
print(data['interfaces'][0]['name'])

What is the expected output if config.json contains {"interfaces": [{"name": "GigabitEthernet0/1"}]}?

Accepted Answer

GigabitEthernet0/1. json.load() reads the file and returns a dict; then accessing the nested structure yields 'GigabitEthernet0/1'.

Answer

None

Answer

interfaces

Answer

Error: list indices must be integers