Networking

Question 1

What is a client?

Answer 1

A device or program that requests and receives services from a server.

Question 2

What is a server?

Answer 2

A program or device that stores and provides data to others in a network.

Question 3

What is the relationship between a client and server?

Answer 3

A client initiates requests for services, which are provided by a server.

Question 4

What do 2xx HTTP status codes indicate?

Answer 4

A request successfully received and accepted by the server.

Question 5

What do 3xx HTTP status codes indicate?

Answer 5

Further action is required to complete the request - typically involves redirection.

Question 6

What do 4xx HTTP status codes indicate?

Answer 6

Client error - there is an issue with the request itself or the client’s actions.

Question 7

What do 5xx HTTP status codes indicate?

Answer 7

Server error meant the server was unable to complete the request.

Question 8

What is HTTP?

Answer 8

Hypertext Transfer Protocol - a set of rules that dictate how information will be transferred between networked devices.

Question 9

What is a HTTP header?

Answer 9

A field of an HTTP request/response that passes additional related metadata - like content-type and autorization.

Question 10

What are HTTP methods used for?

Answer 10

To indicate the action a client would like to perform on a given resource.

Question 11

What is the default HTTP method for the curl command-line tool?

Answer 11

GET; You can also specify a method using -X

Question 12

What is JSON?

Answer 12

JavaScript Object Notation - a data-interchange format designed to send information between different machines/services.

Question 13

What are the benefits of JSON?

Answer 13

• Human & machine-readable
• Lightweight
• Supported by many programming languages

Question 14

What does a DNS (Domain Name System) server do?

Answer 14

It translates human-readable domain names (e.g. www.google.com) into their corresponding IP addresses.

Commonly referred to as a ‘phonebook of the internet’.

Question 15

What is a CLI?

Answer 15

Command-line interface - a text-based interface where you can input commands to interact with a computer’s OS.

Question 16

What does TCP stand for? Where is it used?

Answer 16

Transmission Control Protocol - a networking protocol used for reliable and ordered delivery of data.

Ensures data packets arrive in correct order and w/out corruption.

Question 17

What does UDP stand for? Where is it used?

Answer 17

User Datagram Protocol - a data transport protocol used to send data at speed (connectionless, less reliable than TCP).

Question 18

What is WebSockets? What is used for?

Answer 18

A technology that facilitates bi-directional, real-time communication over a single, consistent TCP connection. It is used for typing notifications, for example.

Question 19

What is an API?

Answer 19

Application Programming Interface - a set of rules governing communication and data exchange between multiple software programs.

Question 20

What are the main features of RESTful APIs?

Answer 20

• Client-server separation
• Stateless
• Caching
• Uniform interface
• Layered system
• Code-on-demand

See here for more detail on each feature (IBM article)

Question 21

Which HTTP method creates a new resource?

Answer 21

POST

Question 22

Which HTTP method retrieves information?

Answer 22

GET

Question 23

What does the PUT HTTP method do?

Answer 23

Overwrites an entire resource with a new version.

Question 24

What does the PATCH HTTP method do?

Answer 24

Applies partial updates to an existing resource.

Question 25

What is a query parameter?

Answer 25

An optional parameter passed in a URL to provide extra information, typically for sorting or filtering results.

Question 26

What does idempotency mean in the context of HTTP methods?

Answer 26

An *idempotent* HTTP method will generate the same result if it is run multiple times as when it is run just once.

Question 27

What is the role of a router in providing Internet connections?

Answer 27

It forwards data packets between computer networks to their intended IP addresses.

Question 28

True or False: Every device globally has a completely unique IP address.

Answer 28

False - every device on a *local* network has a unique IP address.

Question 29

What is a port?

Answer 29

A virtual endpoint within a computer's OS that identifies a specific process or service e.g. port 80 is associated with HTTP. | Helps a computer pass data to applications which can interpret them.

Question 30

What is a context manager? | ```with``` is an example used in Python.

Answer 30

An object used to manage resources, allowing you to allocate and release them as you want. ## Footnote E.g. closing a file after new data has been written to it.

Question 31

What does this common error code mean: `404`

Answer 31

Resource not found on the server.

Question 32

What does this common error code mean: `400`

Answer 32

Bad request ## Footnote This could be due to incorrectly formatted data, an invalid URL etc.

Question 33

What does this common error code mean: `200`

Answer 33

OK ## Footnote The request was received, understood and accepted by the server.

Question 34

What does this common error code mean: `403`

Answer 34

The server does not authorise the request. ## Footnote The user may be authenticated but have insufficient permissions to access the resource.

Question 35

What does this common error code mean: `502`

Answer 35

Bad Gateway ## Footnote A communication issue exists between two servers which need to interact to fulfil the request.

Question 36

What does this common error code mean: `500`

Answer 36

Generic error response - a more specific error code cannot be given to respond to the request.