To History

Domain Name System

• Some authors contend that DNS stands for Domain Name Services or Domain Name Server.

• The Domain Name System (DNS) translates a logical URL into an IP address.
   
• Example: http://www.depaul.edu
  is translated to
  http://140.192.23.180
  
   
  
• 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