1. WHAT IS THE DOMAIN NAME SYSTEM (DNS) ?

2. Overview 1. Introduction to the DNS. 2. How big is the Domain Name System (DNS) ? 3. Components of the DNS. 4. What are the functions of the DNS ? 5. Is the operation of the Domain Name System affected by any legislation in the UK? 6. Significant Limitations to the DNS. 7. Conclusion. 8. References.

3. Introduction to the DNS.  The DNS or Domain Name System is a naming system developed by Paul Mockapetris in 1983 which is used to translate host-names to an IP address and vice versa.  It’s major importance is that it allows users to type easy- to remember domain names (e.g. www.google.com) instead of complex IP addresses (e.g. 173.194.66.106)  Before the use of the DNS, a simple text file called HOSTS.TXT which stored the host names and corresponding IP addresses was used.

4. How big is the Domain Name System (DNS) ?  The size of the Domain Name system can be seen as unlimited or permanently increasing.  This is due to its structure which is hierarchical in design with the with the root domain as the apex (top), followed by global top level domains (e.g..com,.edu,.org ) or country-code top level domains (e.g..uk,.fr ), then sub-domains etc.  This tree of subdivisions may have up to 127 levels and 63 characters per level.

5. How big is the Domain Name System (DNS) ? The picture above shows an example of the hierarchy tree system used by the DNS

6. Components of the DNS.  The are 3 components of the DNS  The name space  The servers/ name servers  The resolvers / name resolution

7. Components of the DNS. The Name Space  The name space is the structure of the DNS database  It is an inverted tree with the root node at the top.  Each node has a label  The root node has a null label, written as “”. The Servers / Name Servers  Name servers store information about the name space in units called “zones”. Each zone has a master name server.

8. Components of the DNS. The Resolvers/Name Resolution  Name resolution is the process by which resolvers and name servers work together to find data in the domain name space.  Only the names and IP addresses of the name servers for the root zone are required for finding information anywhere in the name space

9. What are the functions of the DNS ?  In addition to translating domain name into IP addresses, the DNS has some other functions: One of these functions is caching.  Caching happens in situations when a server collects information about a mapping, it caches that information.  The advantage of this function is that when a similar question about a similar mapping is asked, it can use the cached output, and will not result to additional questions to other servers thus saving time.

10. Is the operation of the Domain Name System affected by any legislation in the UK?  In the UK, there are certain restrictions on TLD (Top Level Domains). For example, the TLD “ac.uk” can only be used by academic institutions.  Also, the TLD “.uk” can not be used by the public alone. It must be used with a second level domain (e.g. co.uk, gov.uk)

11. Significant Limitations to the DNS  Significant limitations of the Domain Name System include:  Lack of support of Unicode characters. This is a major problem for other countries who do not use the Latin (alphabetic) writing system e.g. (Japan).  Also, it currently uses IPv4 instead of IPv6. IPv4 uses 32-bit addresses and this limits the amount of IP address space to 4294967296. Using IPv6 will increase this no by a factor of 7.9x10 28.

12. Conclusion  In Conclusion, although the Domain Name System has its problems, it performs very well and serves billions of users on a daily basis without any major problems.

13. References  Mockapetris, P. (1998). Development of the Domain Name System. Retrieved November 30, 2011, from http://www.cs.rutgers.edu/~badri/552dir/papers/DNS /p112-mockapetris.pdf  Dostálek, L. Kabelová A. (2006). DNS in Action: A detailed and practical guide to DNS implementation, configuration, and administration. Birmingham: Packt Publishing.  DNS Components and General Functions. (2005). Retrieved November 27, 2011, from : http://www.tcpipguide.com/free/t_DNSComponentsandGen eralFunctions.htm  Lacy, J.D. (2002). The reform of United Kingdom company law. London: Cavendish Publishing.

14. References  Waelde, C. (n.d.)Domain names and Trade marks: What's in a name?. Retrieved December 1, 2011, from : http://www.law.ed.ac.uk/it&law/ch4_main.htm  DNS limitations. (n.d.). Retrieved December 2, 2011, from : http://publib.boulder.ibm.com/infocenter/rtca/rtcaic/index.js p?topic=%2Fcom.ibm.storage.rtca.help.doc%2Fad_r_dns_limit. html  Dostálek, L, Kabelová, A, (2006). DNS in action. Olton Birmingham, GBR: Packt Publishing Ltd.