Development of the Domain Name System

This paper discusses the motivation behind the design and need of DNS. Prior to DNS each machine downloaded a file called HOSTS.TXT from the central server on to their system. This file contained the mapping between host names and addresses. This scheme had the inherent problem of distribution and update. With the rise of the number of machines connected to the Internet came the need of building a distributed system for the functionality of HOSTS.TXT.

DNS was designed for this need. It is a hierarchical naming system that had the following design goals:

1. provide all information of HOSTS.TXT
2. Allow distributed implementation of the database
3. Have no size limit issues
4. Be inter-operable
   
5. Provide tolerable performance

DNS contains two main components: name servers and resolvers. Name servers store information and answer queries from the information they possess. Resolvers are the interface to client programs and contain algorithms for querying name servers. DNS name space is organized in the structure of a variable-depth tree. Each node in the tree has a label associated with it and domain name of a node is the concatenation of all the labels on the path from the node to the root of the tree.

One of the main things that makes DNS fast is caching the results of the queries. This overcomes the need to fire a query every time a name lookup has to be performed. Although this optimization comes at the cost of a security concern. People have exploited this feature to perform DNS cache poisoning attacks.

I really enjoyed reading the paper because it gave a good explanation of the ideas behind the design of a system that plays an important role in today's Internet. I would recommend keeping this paper in the syllabus.