The Internet

• Use of Domain Name System (DNS) servers in the access  of a website


  The user enters the domain name/URL which is sent to a DNS serverThe DNS will translate to an IP address which is sent back to the browser If the DNS doesn’t have the IP address, it will request this from a more authoritative serverThe web browser now uses the IP address to request the website/web page that has been requested if it is not already cached by the web browser
• Client Server network


  client computer and server
• Client Role


  Sends requests to server

  waits for reply

  receives reply
• Server Role

  server waits for requests from a client

  performs any processing required to fulfil request

  requested data is sent back to the client
• File server

  holds all the data files and databases

  manages backups
• DNS

  Domain Name System
• DNS function

  used to translate website domain names into IP addresses

  use domain name instead of remembering IP address to access websites

  Network of Domain Name Servers store IP addresses and matching domain names
• Hosting

  service offered by companies that will host web pages and files for websites

  may own web server where website is hosted on
• Advantage of web host

  web hosts have more bandwidth

  web hosts able to monitor equipment 24/7

  web hosts will have backup web sites remotely
• Cloud


  term used to refer to services that are delivered over the Internet
• Uses of The Cloud

  enables users connected to any Internet-enabled computer to access services such as Google Drive or OneDrive
• How DNS Works

  request goes to DNS (e.g. BBC), DNA looks up the domain name in its system and once found sends the IP address to the computer - the computer then uses the IP address to access the website

  If not found it goes to another DNS server and carries on until its found, if not found then an error message will appear