RFC 1386 (rfc1386) - Page 2 of 31

The US Domain

RFC 1386                     The US Domain                 December 1992


1. INTRODUCTION

   1.1 The Internet Domain Name System

   The Domain Name System (DNS) provides for the translation between
   host names and addresses.  Within the Internet, this means
   translating from a name such as "venera.isi.edu", to an IP address
   such as "128.9.0.32".  The DNS is a set of protocols and databases.
   The protocols define the syntax and semantics for a query language to
   ask questions about information located by DNS-style names.  The
   databases are distributed and replicated.  There is no dependence on
   a single central server, and each part of the database is provided in
   at least two servers.

   The assignment of the 32-bit IP addresses is a separate activity.  IP
   addresses are assigned by the Network Information Center
   ().

   In addition to translating names to addresses for hosts that are on
   the Internet, the DNS provides for registering DNS-style names for
   other hosts reachable (via electronic mail) through gateways or mail
   relays.  The records for such name registration point to an Internet
   host (one with an IP address) that acts as a mail forwarder for the
   registered host.  For example, the host "bah.rochester.ny.us" is
   registered in the DNS with a pointer to the mail relay
   "relay1.uu.net".  This type of pointer is called an MX record.

   This gives electronic mail users a uniform mail addressing syntax and
   avoids making users aware of the underlying network boundaries.

   The reason for the development of the domain system was growth in the
   Internet.  The host name to address mappings were maintained by the
   Network Information Center (NIC) in a single file, called HOSTS.TXT,
   which was FTPed by all the hosts on the Internet.  The network
   population was changing in character.  The timeshared hosts that made
   up the original ARPANET were being replaced with local networks of
   workstations.  Local organizations were administering their own names
   and addresses, but had to wait for the NIC to make changes in
   HOSTS.TXT to make the changes visible to the Internet at large.
   Organizations also wanted some local structure on the name space.
   The applications on the Internet were getting more sophisticated and
   creating a need for general purpose name service.  The idea of a
   hierarchical name space, with the hierarchy roughly corresponding to
   organizational structure, and names using "." as the character to
   mark the boundary between hierarcy levels.  A design using a
   distributed database and generalized resources was implemented.

   The domain system provides standard formats for resource data,



Cooper & Postel