History of the Domain
Name System - A.K.A. DNS
In the 1960s, the U.S.
Department of Defense Advanced Research Projects Agency (ARPA, and later
DARPA) began funding an experimental wide area
computer network called the ARPAnet. The ARPAnet used
a centrally administered file called HOSTS.TXT which held all name-to-address
mapping for each host computer connected
to the ARPAnet. Since there were only a handful of host computers at the
start, HOSTS.TXT worked well.
When the ARPAnet moved to
the Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols
and become known as the Internet, the population of the network exploded.
HOSTS.TXT became plagued with problems,
namely:
• traffic and load
• name collisions
• consistency
A replacement for the
HOSTS.TXT file was needed. The goal was to create a system that solved the
problems inherent in a unified host table
system. The new system should allow local administration of data and
also make that data globally available.
In 1984, the architecture
of a new system called Domain Name System (DNS) was designed and is the basis
of the DNS service used today on the Internet.
DNS is a distributed
database that allows local administration of the segments on the overall
database. Data in each segment of the
database are available across the entire network through a client-server
scheme consisting of name servers and
resolvers.
What is a DNS record?
People are much more
comfortable dealing with names rather than strings of numbers. A domain name
such as "lagunainternet.com"
is much easier to remember than the IP address which consists of four octets
of numbers such as 209.132.113.42. Domain
names must be registered with Root Domain Registration Service, such as
Laguna
Beach Internet.
Computers, on the other
hand, prefer numbers to names. Since computers have the final say when a user
is looking for a company Web site, a
mechanism is needed to convert the human-friendly domain name to the computer-friendly
IP address.
DNS records on a DNS
server perform this function. The records translate a domain name to an IP
address; a record equates a domain name
such as "lagunainternet.com" to an IP address such as
209.132.113.42. Once
the domain name has been converted or
"resolved" to an IP address, then (and only then) can the user
connect to your Web site.
Without DNS and domain
names, the user would be required to remember the IP address of every site
they wanted to visit. With DNS servers
and DNS records, customers and their software can easily remember how to
get to your site.
Who manages your DNS records?
Your DNS records can
reside on any server that has the DNS service enabled. To provide DNS service,
InterNIC
requires a site to maintain both a primary and a secondary server.
How does DNS work?
The basic method that allows a domain name to
direct customers to your Web site is shown in Figure 1. This diagram
describes a request made by a Web browser as the customer attempts to log on
to your Web site.
To determine which primary name server contains
your domain name:
1. The local name server (the DNS
resolver/browser machine) contacts the root domain name server maintained
by the serveral Internet root server authorities.
2. The root domain name server returns the IP
address of the primary name server responsible for the requested
domain name.
3. The local name server contacts the primary
name server.
4. The primary name server holds the IP address
information for the domain name in a database and satisfies
the request from the local name server.
5. If the primary name server is unavailable,
the local name server contacts the secondary name server that satisfies
the request from the local name server. The local name server returns to the
Web browser with the IP address for the
requested domain name.
6. Using the IP address, the Web browser
contacts the company Web server.
7. The company Web server sends the Web page to
the local name server.
Figure 1 Basic method of DNS
