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.EDU
Caching: cache response for later
queries
Current implementation
Root servers
Berkeley 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 hierarchy
2. Organizational structuring of
names
3. Datagram access
4. Additional section processing
5. Caching
6. Mail address cooperation
Shortcomings
1. Type and class growth
2. Easy upgrading of applications
3. Distribution of control vs.
distribution of expertise or
responsibility
Future
1. Support for X.500 style address
2. Ubiquitous name service and
consistent name space
3. Solutions to the growing
complexity of naming.
Questions?