Web Protocols

Explain how email protocols operate.

Hypertext Transfer Protocol and Hypertext Markup Language

When a web address or Uniform Resource Locator (URL) is typed into a web browser, the web browser establishes a connection to the web service. The web service is running on the server that is using the HTTP protocol. To better understand how the web browser and web server interact, examine how a web page is opened in a browser.

• Step 1 The browser interprets the three parts of the URL:
  • http (the protocol or scheme)
  • www.cisco.com (the server name)
  • index.html (the specific filename requested)

• Step 2 The browser then checks with a name server to convert www.cisco.com into a numeric IP address, which it uses to connect to the server. The client initiates an HTTP request to a server by sending a GET request to the server and asks for the index.html file.

• Step 3 In response to the request, the server sends the HTML code for this web page to the browser.

• Step 4 The browser deciphers the HTML code and formats the page for the browser window.

HTTP and HTTPS

• HTTP is a request/response protocol that specifies the message types used for that communication.
• The three common message types are GET, POST, and PUT:
  • GET – This is a client request for data. A client (web browser) sends the GET message to the web server to request HTML pages.
  • POST – This uploads data files to the web server, such as form data.
  • PUT – This uploads resources or content to the web server, such as an image.

Note: HTTP is not a secure protocol. For secure communications sent across the internet, HTTPS should be used.

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