HTTP Basics

Question 1

What does HTTP stand for?

Answer 1

HyperText Transfer Protocol

Question 2

What is HTTP?

Answer 2

It is a critical protocol used to transfer data across the web.

Question 3

How many types of headers did the first version of HTTP have?

Answer 3

One => GET which requests a page from a server.

BONUS: The response from the server was always an HTML page.

Question 4

What was the first version of HTTP?

Answer 4

Version 0.9

Question 5

What is the current version and when was it last updated?

Answer 5

1.1 and last revised in 2014

Question 6

Is HTTP a:

1. Command and Response Text-Based protocol using client-server communication models.
2. Request and Function-based protocol using cloud servers
3. A protocol to keep your computer safe from viruses
4. Request and Response Object-Oriented protocol using client-server communication models.

Answer 6

1. Command and Response Text-Based protocol using client-server communication models.

Question 7

HTTP is a stateless protocol. What does that mean?

Answer 7

That means that the server isn’t required to store session information, and each request is independent of the other.

Question 8

Why are independent requests important in HTTP?

Answer 8

Because any type of data (file, binary, text, etc..) can be sent by HTTP. The only thing necessary is that server and client should know how to handle that request

Question 9

What is the request and response message structure?

Answer 9

The request and response have the same structure as shown in the image.

Question 10

What does a request consist of?

Answer 10

A command or request + optional headers + optional body content.

Question 11

What does a response consist of?

Answer 11

A status code + optional headers + optional body content.

Question 12

What is CRLF?

Answer 12

It stands for:

Carriage Return and Line Feed

and a simple CRL combination is used to delimit the parts, and a single blank line (CRLF ) indicates end of the headers.

If the request or response contains a message body then this is indicated in the header.

Question 13

How is the start line of the request formatted?

Answer 13

Method + Resource Path + protocol version

Example: if we try to access the web page testpage.htm on www.testsite5.com

The the start line of the request would be

GET /testpage.htm HTTP/1.1

Where

GET is the method

/testpage.htm is the relative path to the resource.

HTTP/1.1 is the protocol version we are using

Question 14

Does a relative path include the domain name?

Answer 14

NO

Question 15

When we enter the URL what does the browser do with it?

Answer 15

It uses it to create the relative URI of the resource.

Note: URL (uniform resource Locator) is used for web pages. It is an example of a URI (uniform resource indicator).

Question 16

Is the actual HTTP request shown by the browser?

Answer 16

No. Unless of course, you use a special tool like HTTP Header Live (like in FireFox).

Question 17

What is the difference between the URL vs HTTP?

Answer 17

• The HTTP stands for Hyper Text Transfer Protocol and the URLS stands for Uniform Resource Locator.
• The URL is the web address of the particular website and it tells the web browser the address of the resource to locate and the protocol to use to retrieve that resource (HTTP).
• HTTP is the transfer protocol that transfers the resource (web page, image, video, etc) from the server to the client.

The URL can also include the port which is normally hidden by the browser, but you can manually include it as shown in the second image with the port

Question 18

What does each HTTP Response consist of?

Answer 18

• STATUS code And Description
• 1 or more optional headers
• Optional Body message can be many lines including binary data

Question 19

What is the range of response status codes and their general meanings?

Answer 19

• 1xx – Informational
• 2xx – Successful
• 3xx - Multiple Choice
• 4xx – Client Error
• 5xx - Server Error

For example, a successful page request will return a 200 response code and an unsuccessful 400 response code.

You can find a complete list and their meaning here

Question 20

The image shows a Request and Response rendered in the browser. That being the case, what do you imagine the HTTP request-response looks like behind the scenes?

Answer 20

Notice the request headers are automatically inserted by the browser, and so are the response headers are inserted by the web server.

There is no body content in the request. The body content in the reply is a web page, and is shown in the browser, and not by the live headers tool.

Question 21

What are the two most common types of HTTP request methods?

Answer 21

GET and POST

Question 22

The HTTP protocol now support 8 request types, also called methods or verbs in the documentation. What are they and what’s their purpose?

Answer 22

• GET – Requesting resource from server
• POST – submitting a resource to a server (e.g. file uploads)
• PUT - As POST but replaces a resource
• DELETE - Delete a resource from a server
• HEAD – As GET but only return headers and not content
• OPTIONS - Get the options for the resource
• PATCH - Apply modifications to a resource
• TRACE - Performs message loop-back

GET is for getting web pages and POST is for submitting web forms.

The Other methods are used when working with Web and IOT APIs specifically put, delete and head.