The Domain Name System (DNS) – The online directory DNS Simplified

 Large internet directory, connecting people to information.  Information on the internet is located at different Internet Protocol(IP) addresses.  Translates Domain Names into IP addresses.  No need to remember long complex IP addresses. What is the Domain Name System?

Example:  Google IP addresses ( Mitchell,B )        What is the DNS - Examples } All of these IP addresses are linked to the Domain Name GOOGLE.

How the Domain Name System Works How the DNS works

 More than 215million Domain Names have been registered across the Top Level Domains (TLD)  TLD Increase of 16.9 Million (8.2%) within one year. Size of the Domain Name System Verisign

IPv4:  IPv4 – First Internet Addressing System to connect user to services on the Internet.  32Bit Addressing System – Space Limited to 4,294,967,296 IP Addresses.  Ran out on February 3 rd 2011 IPv6:  New addressing system – IPv6 (Internet Protocol Version 6)  128Bit Addressing System – Space limited to 340 undercillion (2^128) possible IP addresses Size of Domain Name System IPv4 and IPv6

GOOGLE.CO.UK  255 Max number of characters  Same name allowed, but root must be different. Important DNS Components Name Space Name space tree Top Level Domain 2 nd Level Domain 3 rd Level Domain

Important DNS Components Name Server  Translates Domain Names to IP Addresses  Larger websites have multiple IP addresses  Each domain has a minimum of 2 name servers cs-faculty.stanford

Important DNS Components Resolver  Queries Domain Name System for information.  Checks information received for errors  Prevents errors and ensures data can be read correctly. Resolver

 UK websites governed by Nominet  Some Domain Limited to location or sector e.g.:.gov – government services.police – police services in UK.NHS.UK – National Heath Service in UK  Trademarks Domain Name System UK Legislation

 Name System  Name Space Limited to 255 characters  IPv4 (4,294,967,296 IP Addresses) – February 3 rd 2011 Limitations To the DNS

Thank You

 DNS Simplified. (n.d). Retrieved from:  Google IP - Mitchell, B. (n.d). What Is the IP Address of Google?. Retrieved from:  Verisign. (2 nd February 2011). Retrieved from  Name Space Tree. (n.d). Retrieved from: bio3d.colorado.edu via Google.  cs-faculty.stanford. (30 th May 2011). Retrieved from: faculty.stanford.edu/~eroberts/cs181/projects/ /FreedomOfInformationChina/author/martyhu/index.htmlhttp://www-cs- faculty.stanford.edu/~eroberts/cs181/projects/ /FreedomOfInformationChina/author/martyhu/index.html  resolver. (5 th November 2011). Retrieved from:  How the DNS works.(n.d).Retrieved from &(May 14 th, 2009). Retrieved from : najcolabs.com/?tag=dnswww.howstuffworks.com/dns.htm References