Domain Name Servers (DNS)

• IP address


  Every device connected to the Internet has its own IP address
• Website


  To access a website, you connect to a specific web server that holds that website
• You can enter the IP address of the web server directly into the web browser to access the website
• IP addresses


  Difficult to remember, no one knows the IP address of Google or YouTube
• Domain name


  Much better than IP addresses, we're familiar with what the meanings are (e.g. youtube.com, facebook.com)
• DNS (Domain Name System)

  Translates between domain names and IP addresses
• Domain name server


  Special-purpose servers that contain a database of IP addresses and their corresponding domain names
• Accessing a website using a domain name


  1. User types in domain name

  2. Browser contacts DNS server to check for IP address

  3. DNS server checks its database and if not found, contacts other DNS servers until IP address is found

  4. DNS server returns IP address to browser

  5. Browser can then connect to website using the IP address
• The domain name system is a client-server network, but the server can also act as a client to other DNS servers
• There is not one massive DNS server that everyone uses, it is a network of DNS servers