To Brief History

Domain Name Servers

• A Domain Name Server (DNS) translates a logical URL into an IP address.
   
• Example: http://www.depaul.edu
  is translated to
  http://140.192.220.35
  
   
  
• The parts of this logical Uniform Resource Locator (URL):
  http://www.depaul.edu
  

  http	Protocol
  edu	Top level domain (TLD)
  depaul	Second level domain
  www	Web server name

  
   
  
• Some common TLDs:
  
  com    edu    gov    mil    net    org
   
   
  
• Many countries have their own TLD:
  
  au    ca    de    fr    uk
   
   
  
• More URLs:
  

  www.yahoo.com	A famous search engine site
  encarta.msn.com	A Web server that does not start with www
  www.bbc.co.uk	A name using four parts rather than three
  ftp.microsoft.com	An FTP server rather than a Web server

  
   
  
• Steps to display a web document in a browser:
  
  • User enters URL of web document in browser.
  • Browser gets IP address of server from DNS.
  • Browser gets web document from server.
  • Browser displays web document.