PCPP1 Networking And Restful Apis — 20 Questions

Question 1

When working with raw sockets, what does the 'socket.SOCK_STREAM' constant represent?

Accepted Answer

TCP connection-oriented sockets. SOCK_STREAM is used for TCP connections, which are connection-oriented and reliable.

Answer

UDP datagram sockets

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Raw network sockets

Answer

Unix domain sockets only

Question 2

You are using the socket module to create a TCP client. After creating the socket object, which method call is required to establish a connection to a remote server listening on 192.168.1.50 at port 8080?

Accepted Answer

sock.connect(('192.168.1.50', 8080)). The connect method is used on a client-side socket to initiate a TCP three-way handshake with a remote server.

Answer

sock.bind(('192.168.1.50', 8080))

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sock.accept()

Answer

sock.listen(1)

Question 3

You are consuming a REST API that returns data in JSON format. After calling response.json(), you notice the data contains nested dictionaries. What is the most Pythonic way to handle a missing key in the response dictionary safely?

Accepted Answer

Use response.json().get('key', default_value). The dict.get() method provides a way to access a key with a default value if the key does not exist, preventing a KeyError.

Answer

Wrap the access in a try-except KeyError block

Answer

Check 'if 'key' in response.json():' before access

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Use response.json()['key'] and assume the API schema is always correct

Question 4

When using the 'socket' module, what is the effect of calling 'socket.settimeout(5.0)' on a socket object?

Accepted Answer

It causes the operation to raise a socket.timeout after 5 seconds. The settimeout() method sets a timeout in seconds for subsequent socket operations. If the operation does not complete within the time, a socket.timeout exception is raised.

Answer

It sets the send buffer size to 5.0 bytes

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It blocks the thread for exactly 5 seconds

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It forces the socket to close after 5 seconds of inactivity

Question 5

In the 'requests' library, which HTTP method is typically used to update an existing resource on a server?

Accepted Answer

PUT. The PUT method is standard for replacing or updating an existing resource at a specific URI.

Answer

POST

Answer

GET

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DELETE

Question 6

You are building a REST client that needs to handle 429 Too Many Requests status codes. Which strategy is most effective when implementing an automatic retry mechanism?

Accepted Answer

Implement an exponential backoff strategy with jitter. Implementing exponential backoff ensures that you do not overwhelm the server while waiting for the rate limit to reset.

Answer

Switch to a different base URL immediately

Answer

Ignore 429 errors and continue execution

Answer

Retry immediately in a loop until successful

Question 7

When using the 'requests' library to perform a GET request, which parameter should be passed to the 'params' argument to include query string parameters in the URL?

Accepted Answer

A dictionary. The 'params' argument expects a dictionary of key-value pairs which the library automatically encodes and appends to the URL.

Answer

A tuple of values

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A single formatted string

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A list of strings

Question 8

You are developing a multithreaded HTTP scraper. When using the 'requests' library inside 'threading.Thread' objects, what is the recommended practice for handling session persistence?

Accepted Answer

Initialize a new Session object inside each thread's run method. Requests.Session objects are not thread-safe in a way that prevents race conditions on connection pools. Each thread should ideally have its own session or a thread-safe connection pool mechanism.

Answer

Wrap the session object in a threading.Lock

Answer

Share a single global Session object across all threads

Answer

Disable connection pooling using 'pool_connections=0'

Question 9

When using 'requests.get()', how can you include a custom HTTP header in your request?

Accepted Answer

Use the 'headers' dictionary argument. The 'headers' parameter accepts a dictionary of HTTP headers.

Answer

Use the 'data' argument

Answer

Pass it as part of the URL string

Answer

Use the 'params' dictionary

Question 10

What is the purpose of the 'socket.shutdown()' method in Python?

Accepted Answer

It stops further communication on the socket. shutdown() allows you to stop sending or receiving data on a socket while keeping the file descriptor open.

Answer

It forces the socket to release its memory

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It resets the socket connection immediately

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It closes the file descriptor completely

Question 11

Which status code indicates that a requested resource has been successfully created?

Accepted Answer

201 Created. 201 Created is the standard HTTP response for successful resource creation.

Answer

400 Bad Request

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200 OK

Answer

204 No Content

Question 12

You are using 'concurrent.futures.ThreadPoolExecutor' to fetch data from multiple REST APIs. What happens if an exception is raised inside a thread?

Accepted Answer

The exception is stored and raised when calling future.result(). Exceptions raised in a future are captured and re-raised when calling result() on the Future object returned by submit().

Answer

The exception is ignored by the ThreadPoolExecutor

Answer

The entire program crashes immediately

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The thread dies silently without notification

Question 13

You need to send binary data over a socket. Which method should you use on the socket object to ensure all data is sent?

Accepted Answer

sendall(). The sendall() method continues to transmit data from the buffer until all data has been sent or an error occurs.

Answer

write()

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send()

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recv()

Question 14

Which of the following headers is commonly used in REST APIs to indicate the format of the request body?

Accepted Answer

Content-Type. The 'Content-Type' header tells the server what type of media is being sent in the request body.

Answer

Authorization

Answer

Accept

Answer

User-Agent

Question 15

In a multithreaded network application, you observe 'ConnectionResetError'. What is the most likely cause when using Python sockets?

Accepted Answer

The remote server closed the connection abruptly. This occurs when the remote host closes the connection while the local end is still trying to send or receive data.

Answer

The port is already in use by another process

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The socket was never bound

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The local thread pool is exhausted

Question 16

You are parsing a JSON response that contains a large list of objects. Which technique is most memory-efficient for processing these objects?

Accepted Answer

Iterate through the list object after parsing. If you have control over the response, streaming the JSON or processing it iteratively (if supported by the parser) saves memory.

Answer

Convert the entire JSON to a string then split

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Use the 'json.loads()' method on the full response

Answer

Use a custom regex to parse the JSON

Question 17

What is the primary difference between the 'socket.AF_INET' and 'socket.AF_INET6' address families?

Accepted Answer

AF_INET is for IPv4; AF_INET6 is for IPv6. AF_INET is for IPv4, while AF_INET6 is for IPv6 addressing.

Answer

AF_INET6 supports UDP only

Answer

AF_INET requires a password

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AF_INET is faster than AF_INET6

Question 18

Which module provides a high-level API for working with URLs, such as parsing and unparsing them?

Accepted Answer

urllib.parse. The 'urllib.parse' module is designed for splitting and joining URL components.

Answer

requests

Answer

socket

Answer

http.client

Question 19

When receiving data from a TCP socket using 'recv(buffer_size)', what does the returned value represent?

Accepted Answer

The data as a byte string. The method returns the bytes received, up to the specified buffer size.

Answer

A boolean indicating connection status

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The total number of bytes in the stream

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The number of packets received

Question 20

You are investigating a network bottleneck in your Python application using `requests`. If you aren't using a `Session` object, what performance-related behavior should you expect?

Accepted Answer

Each request will perform a full TCP handshake. Without a Session, each request creates a new TCP connection, incurring the cost of a three-way handshake every time.

Answer

The application will use more memory

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Connection pooling will be enabled by default

Answer

The server will block your IP immediately