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

2.  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?

3. Example:  Google IP addresses ( Mitchell,B )  64.233.160.0 - 64.233.191.255  66.102.0.0 - 66.102.15.255  66.249.64.0 - 66.249.95.255  72.14.192.0 - 72.14.255.255  74.125.0.0 - 74.125.255.255  209.85.128.0 - 209.85.255.255  216.239.32.0 - 216.239.63.255 What is the DNS - Examples } All of these IP addresses are linked to the Domain Name GOOGLE.

4. How the Domain Name System Works How the DNS works

5.  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

6. 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

7. 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

8. 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

9. 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

10.  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

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

12. Thank You

13.  DNS Simplified. (n.d). Retrieved from: http://websiteincite.com/diagrams/sm_dns.jpghttp://websiteincite.com/diagrams/sm_dns.jpg  Google IP - Mitchell, B. (n.d). What Is the IP Address of Google?. Retrieved from: http://compnetworking.about.com/od/traceipaddresses/f/google-ip-address.htm http://compnetworking.about.com/od/traceipaddresses/f/google-ip-address.htm  Verisign. (2 nd February 2011). Retrieved from http://www.verisigninc.com/assets/domain-name-report-feb-2011.pdf http://www.verisigninc.com/assets/domain-name-report-feb-2011.pdf  Name Space Tree. (n.d). Retrieved from: bio3d.colorado.edu via Google.  cs-faculty.stanford. (30 th May 2011). Retrieved from: http://www-cs- faculty.stanford.edu/~eroberts/cs181/projects/2010- 11/FreedomOfInformationChina/author/martyhu/index.htmlhttp://www-cs- faculty.stanford.edu/~eroberts/cs181/projects/2010- 11/FreedomOfInformationChina/author/martyhu/index.html  resolver. (5 th November 2011). Retrieved from: http://www.bladeblue.com/helpdesk/dns-propagation/ http://www.bladeblue.com/helpdesk/dns-propagation/  How the DNS works.(n.d).Retrieved from www.howstuffworks.com/dns.htm &(May 14 th, 2009). Retrieved from : najcolabs.com/?tag=dnswww.howstuffworks.com/dns.htm References