HTTP

TCP

With persistent connections, the server leaves the connection open after sending responses and hence the subsequent requests and responses between the same client and server can be sent.

HTTP

If a website uses instead of , all requests and responses can be read by anyone who is monitoring the session.

HTTP method

A(n) , usually a verb like GET, POST or a noun like OPTIONS or HEAD that defines the operation the client wants to perform.

nonpersistent connection

A(n) is the one that is closed after the server sends the requested object to the client.

HTTP response status codes

indicate whether a specific HTTP request has been successfully completed.

Bad Request

400 : The server could not understand the request due to invalid syntax.

HTTP

can use both nonpersistent connections and persistent connections.

Nonpersistent connections

are the default mode for HTTP /1.0 and persistent connections are the default mode for HTTP /1.1.

User-Agent

curl/7.36.0 lib.curl/7.63.0 OpenSSl/1.1.1 zlib/1.2.11

Host

www.example.com

Accept-Language

en

Server

Apache

Accept-Ranges

bytes

Content-Length

12

Vary

Accept-Encoding

Content-Type

text/plain

User-Agent

curl/7.36.0 lib.curl/7.63.0 OpenSSl/1.1.1 zlib/1.2.11

Host

www.example.com

Accept-Language

en

The path of the resource to fetch; the URL of the resource stripped from elements that are obvious from the context, for example without the protocol (http

/ ), the domain (here, google.com), or the TCP port

100 Continue

This interim response indicates that everything so far is OK and that the client should continue the request, or ignore the response if the request is already finished

200 OK

The request has succeeded

GET

The resource has been fetched and is transmitted in the message body

HEAD

The entity headers are in the message body

PUT or POST

The resource describing the result of the action is transmitted in the message body

TRACE

The message body contains the request message as received by the serve

301 Moved Permanently

The URL of the requested resource has been changed permanently

400 Bad Request

The server could not understand the request due to invalid syntax

500 Internal Server Error

The server has encountered a situation it doesn't know how to handle