Development of the domain name system

Baoning Wu

01/30/2003

What is DNS?

DNS is the largest name services today.

Domain name to IP address

The content of this paper

Examine the ideas behind the initial design of the DNS in 1983.

Discuss the evolution of the ideas into the current implementations and usages.

Surprises, successes and shortcomings.

To predict its future.

Genesis of DNS

The HOSTS.TXT system was encountering problems, e.g,

(1) the file and the costs of its distribution were too large

(2) the centralized control of updating did not fit the trend toward more distributed management of the Internet.

DNS design assumptions

Provide at least all of the same information as HOSTS.TXT

Allow the database to be maintained in a distributed manner

Have no obvious size limits for names, name components

Interoperate across the DARPA Internet and in as many other environments as possible

Provide tolerable performance

Architecture

Name servers: repositories of information, and answer queries using whatever information they possess

Resolvers: interface to client program, embody the algorithms necessary to find a name server

concepts

Name space: is a variable-depth tree where each node in the tree has an associated label.

RR (resource records) in DNS : each RR carries a well-known type and class field e.g.

<Name, Value,TTL,Class,Type>< "foo.example.com",

10.1.2.3, TTL => 86400, Class => "IN", Type => "A“>

Database distribution

Zones: a complete description of a contiguous section of the total tree name space.

EDU and ISI.EDUCaching: cache response for later

queries

Current implementation

Root serversBerkeley BIND

Surprises

1. Refinement of semantics: the info is not well-understood

2. Performance: much worse than the original design expected

3. Negative caching: high percentage of negative responses

Successes

1. Variable depth hierarchy2. Organizational structuring of

names3. Datagram access4. Additional section processing5. Caching6. Mail address cooperation

Shortcomings

1. Type and class growth2. Easy upgrading of applications3. Distribution of control vs.

distribution of expertise or responsibility

Future

1. Support for X.500 style address2. Ubiquitous name service and

consistent name space3. Solutions to the growing

complexity of naming.

Questions?