1. The Domain Name System: What Does It Mean For You?

2. Introduction Size of the DNS Important Components for the DNS
Function of the DNS
Legislation affecting the DNS
Limitation of continued DNS operation

3. Facts of the DNS
Some things you may not know about domain names: There are 17,576 possible three-letter combinations, and all of them are registered. The most popular name is 11 characters long.
(Yamato, 2006)
Google – 6 characters
Facebook – 8 characters
Pinnacle Studios (pinnaclesys.com) – 11 characters

4. What is the DNS? DNS forms a backbone for the internet.
Typical IP address
The potential problem
The DNS forms a backbone for the internet. It allows names to be used as internet address, i.e. instead of typing in a sequence of four groups of numbers known as an Internet Protocol address (IP address.)
A typical IP address can be something like to
The problem: You could find yourself on a completely different website by mistyping one number.

5. Size of the DNS Central DNS server? 13 DNS Root servers untrue
There can be up to 127 branches from the main domain tree which each label up to 63 characters in length. However there can only be a total of 253 characters in the full name.
(Domain Name System, 2011)
There is no specific “central DNS server” – all the DNS information is stored on various different servers worldwide. Furthermore to this any information on internal company web pages are stored on the company’s own DNS server.
There is some confusion over the number of DNS servers in use – the actual fact is that there are some 250 in existence with 12 organisations responsible for the management of the servers.
(Davies, 2007)

6. root-servers.org, 2011
This image, screen-shotted from the website shows locations of DNS servers around the world. At this time there were 259 DNS servers.

7. Following from the previous image, this screenshot of the same website shows the location and organisation responsible for the various servers.
The server letters indicate the location on the world map of all the servers under the relevant organisation’s control.

8. Components of the DNS The Name Space The Name Server The Resolver
(DNS Components, 2006)

9. The Name Space Allows structure of domain name to be formed
Each name is assigned its own Name Space
Domain Tree operates opposite to an ordinary tree
The Name Space allows for the structure of the website address. Each name within an address is assigned its own Name Space so it is clear where it fits in under the hierarchy of the domain tree.
The tree works backwards to an ordinary tree in that the root (i.e. Google) is at the top. The address branches out so the .co.uk is the Top Level Domain (TLD) and other addresses continue out. (Rampling B, 2003)

10. The Name Server Authoritative Server Recursive and Caching Server
Master Server
Slave Server
Recursive and Caching Server
The name server maps how addresses are to be translated.
The Authoritative server provides the general lookup facilities. It answers any DNS queries about the various domains. The Master Authoritative server does the actual lookups for the queries, and the slave server functions as backup to the master server by duplicating its tasks so as to speed up response time. It can also assist the master server by performing its own lookups if the workload is high.
(What Is Authoritative Name Server?, 2011)
The Recursive and Caching Server functions like an archive. It can be programmed to store answers for some of the more common DNS queries and can issue these responses automatically, leave the Authoritative server free to deal with the other queries.
(Name Server, 2011)

11. The Resolver Translates domain names to IP addresses and vice versa
Essential that it is done both ways
The Resolver is the final component of the DNS. Its task is to transform domain names into IP addresses and back again. This has to be done both ways in order to ensure that the correct IP address is sent, a domain name is received back after it has been through the DNS lookup.

12. Function of the DNS Lookup facility for the Internet
Forward Lookup Zone
Backward Lookup Zone
DNS Shutdown in Egypt
The DNS functions as a lookup facility for the internet. It translates the name of a website into its relevant IP address (Forward Lookup) and re-translates the IP address back into a name when returning it to the user. (Backward Lookup.)
An example of returning the address to the user is under a search engine. If the DNS did not work both ways, the website addresses in the search engine would all appear as IP addresses and it would be rather difficult to know which address was wanted.
A news article showed how much effect shutting down DNS has caused. The particular instance showed Egypt's internet traffic virtually non existent due to the Government ordering the Internet Service Providers (ISPs) to shut down all their internet routing. This action disconnected Egypt from the rest of the world, and then the DNS servers in Egypt were also shut down it meant that residents inside Egypt were unable to communicate internally in the country. This occurred on 27th January (Herrmann, 2011)
The following image shows the internet usage in Egypt before and after the shutdown.

13. Shutting down both the ISP routing and DNS servers effectively disconnected Egypt from the rest of the world.
Some people still had internet access as they were able to use mobile phones etc to contact ISPs outside of Egypt, but the majority lost connection.
(Cellan-Jones, 2011)

14. Legislation affecting the DNS
Domain name that the company wants is already registered
Larger companies can potentially bully smaller companies and individuals if they want a domain name
Many legal issues arise where a company wants a domain name as their company name, but find out that this has already been registered by someone else. There is no right for a company to have a domain name simply because it wants it – the domain name allocations are done on a first-come, first-served basis.
Furthermore, some people who saw domain name registrations as a way to make money had realised that if they registered a domain name for themselves under the same name as a large shopping centre, then they could make the shopping centre pay to buy the domain name.

15. Legislation affecting the DNS
Laws on domain name extensions only
There are regulations that certain domain names that can only be used for specific purposes – i.e. .edu is only for education institutions, .gov is for government use.

16. Limitations of DNS operation
IP Protocol
IPv4
IPv6
IPv4 – 4.3 billion IP addresses
IPv6 – 340 unidecillion IP addresses (34x1039)
(IPv6, 2011)
34,000,000,000,000,000,000,000,000,000,000,000,000,000
The DNS system itself is not limited in its operation – it is the capabilities from IPv4 which limit the function of the DNS. Under IPv4 the addressing functions as 32bit, whereas the newer IPv6 works on 128bit addressing.

17. Conclusion DNS is a very large topic
Technology and the Internet is constantly changing
The topic of the DNS is a very large topic – there is a massive amount of information available regarding it. This presentation has aimed to quickly run through the basic items which make the DNS work, from its functionality through to its limitations.
Technology and the Internet is constantly changing – the transition from IPv4 to IPv6 is evidence of this. As a result, people who use the Internet should have an idea of what goes in the background.

18. Thank you for your attention

19. Bibliography References
Cellan-Jones, R, , Only connect ... Retrieved from Domain Name System, Retrieved from DNS Components, 26th April Retrieved from (uploader user name listed as Alvin) DNS Server Support Image (on video) Retrieved from Herrmann, S, , Egypt severs internet connection amid growing unrest, BBC News Technology. Retrieved from (Author identifed as Herrmann S from ) IPv6, Retrieved from K Davies, 2007, November 15. There are not 13 root servers. Retrieved from servers/ Name Server, Retrieved from Rampling B, DNS, 2003, The DNS Namespace. (document as text and embedded video), Retrieved from root-servers.org Retrieved from What is Authoritative Name Server? Retrieved from Yamato M, 2006, Fun facts about domain names,