200-901 Software Development and Design — 40 Questions

Question 1

In a RESTful API, which HTTP method is idempotent but not safe?

Accepted Answer

DELETE. Both DELETE and PUT are idempotent methods that can modify resources, meaning they are not safe. GET is safe and idempotent. POST is neither.

Answer

GET

Answer

POST

Question 2

A Python script is interacting with a REST API that returns JSON. The script needs to handle potential errors gracefully. Which TWO practices should be implemented? (Choose two.)

Accepted Answer

Use response.raise_for_status() to raise exceptions for HTTP errors.. Options A and C are both correct practices when interacting with a REST API using the Python requests library. Option A: `response.raise_for_status()` is a method that automatically raises an exception for HTTP error status codes (4xx and 5xx), allowing structured error handling via try/except. Option C: Directly checking `response.status_code` gives fine-grained control to handle different status codes as needed. Both approaches are complementary and recommended. The incorrect options: B (single try/except without differentiation) is poor practice as it treats all exceptions the same. D (assuming success) ignores error handling. E (always parsing with json.loads) fails if content is not JSON.

Answer

Use a single try/except block to catch all exceptions without differentiation.

Answer

Assume the request always succeeds; errors are rare.

Answer

Always parse the response body with json.loads() regardless of content type.

Question 3

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 4

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). 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 5

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. `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 6

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 7

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 8

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 9

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 10

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]. 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 11

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 12

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 13

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 14

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 15

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 16

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 17

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). Options A and C are valid Python exception handling statements. Option A uses the correct `as` keyword to bind the exception instance. Option C shows proper syntax with multiple except blocks, where a generic `except:` can follow a specific except. Option B is invalid because it uses the obsolete comma syntax (`except ZeroDivisionError, e`), removed in Python 3. Option D is invalid because you cannot catch multiple exception types with a single `as` variable using a tuple; the syntax is not supported. Option E is invalid because a bare `except:` clause is considered poor practice and is not a valid 'exception handling statement' in this context—it catches all exceptions without specificity.

Answer

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

Answer

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

Answer

try:
    x = 1/0
except:
    print('error')

Question 18

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 19

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']. 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 20

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)