rfc1591.txt

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Network Working Group                                          J. Postel
Request for Comments: 1591                                           ISI
Category: Informational                                       March 1994


              Domain Name System Structure and Delegation


Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

1. Introduction

   This memo provides some information on the structure of the names in
   the Domain Name System (DNS), specifically the top-level domain
   names; and on the administration of domains.  The Internet Assigned
   Numbers Authority (IANA) is the overall authority for the IP
   Addresses, the Domain Names, and many other parameters, used in the
   Internet.  The day-to-day responsibility for the assignment of IP
   Addresses, Autonomous System Numbers, and most top and second level
   Domain Names are handled by the Internet Registry (IR) and regional
   registries.

2.  The Top Level Structure of the Domain Names

   In the Domain Name System (DNS) naming of computers there is a
   hierarchy of names.  The root of system is unnamed.  There are a set
   of what are called "top-level domain names" (TLDs).  These are the
   generic TLDs (EDU, COM, NET, ORG, GOV, MIL, and INT), and the two
   letter country codes from ISO-3166.  It is extremely unlikely that
   any other TLDs will be created.

   Under each TLD may be created a hierarchy of names.  Generally, under
   the generic TLDs the structure is very flat.  That is, many
   organizations are registered directly under the TLD, and any further
   structure is up to the individual organizations.

   In the country TLDs, there is a wide variation in the structure, in
   some countries the structure is very flat, in others there is
   substantial structural organization.  In some country domains the
   second levels are generic categories (such as, AC, CO, GO, and RE),
   in others they are based on political geography, and in still others,
   organization names are listed directly under the country code.  The
   organization for the US country domain is described in RFC 1480 [1].




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RFC 1591      Domain Name System Structure and Delegation     March 1994


   Each of the generic TLDs was created for a general category of
   organizations.  The country code domains (for example, FR, NL, KR,
   US) are each organized by an administrator for that country.  These
   administrators may further delegate the management of portions of the
   naming tree.  These administrators are performing a public service on
   behalf of the Internet community.  Descriptions of the generic
   domains and the US country domain follow.

   Of these generic domains, five are international in nature, and two
   are restricted to use by entities in the United States.

   World Wide Generic Domains:

   COM - This domain is intended for commercial entities, that is
         companies.  This domain has grown very large and there is
         concern about the administrative load and system performance if
         the current growth pattern is continued.  Consideration is
         being taken to subdivide the COM domain and only allow future
         commercial registrations in the subdomains.

   EDU - This domain was originally intended for all educational
         institutions.  Many Universities, colleges, schools,
         educational service organizations, and educational consortia
         have registered here.  More recently a decision has been taken
         to limit further registrations to 4 year colleges and
         universities.  Schools and 2-year colleges will be registered
         in the country domains (see US Domain, especially K12 and CC,
         below).

   NET - This domain is intended to hold only the computers of network
         providers, that is the NIC and NOC computers, the
         administrative computers, and the network node computers.  The
         customers of the network provider would have domain names of
         their own (not in the NET TLD).

   ORG - This domain is intended as the miscellaneous TLD for
         organizations that didn't fit anywhere else.  Some non-
         government organizations may fit here.

   INT - This domain is for organizations established by international
         treaties, or international databases.

   United States Only Generic Domains:

   GOV - This domain was originally intended for any kind of government
         office or agency.  More recently a decision was taken to
         register only agencies of the US Federal government in this
         domain.  State and local agencies are registered in the country



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RFC 1591      Domain Name System Structure and Delegation     March 1994


         domains (see US Domain, below).

   MIL - This domain is used by the US military.

   Example country code Domain:

   US - As an example of a country domain, the US domain provides for
        the registration of all kinds of entities in the United States
        on the basis of political geography, that is, a hierarchy of
        <entity-name>.<locality>.<state-code>.US.  For example,
        "IBM.Armonk.NY.US".  In addition, branches of the US domain are
        provided within each state for schools (K12), community colleges
        (CC), technical schools (TEC), state government agencies
        (STATE), councils of governments (COG),libraries (LIB), museums
        (MUS), and several other generic types of entities (see RFC 1480
        for details [1]).

   To find a contact for a TLD use the "whois" program to access the
   database on the host rs.internic.net.  Append "-dom" to the name of
   TLD you are interested in.  For example:

                       whois -h rs.internic.net us-dom
      or
                       whois -h rs.internic.net edu-dom

3.  The Administration of Delegated Domains

   The Internet Assigned Numbers Authority (IANA) is responsible for the
   overall coordination and management of the Domain Name System (DNS),
   and especially the delegation of portions of the name space called
   top-level domains.  Most of these top-level domains are two-letter
   country codes taken from the ISO standard 3166.

   A central Internet Registry (IR) has been selected and designated to
   handled the bulk of the day-to-day administration of the Domain Name
   System.  Applications for new top-level domains (for example, country
   code domains) are handled by the IR with consultation with the IANA.
   The central IR is INTERNIC.NET.  Second level domains in COM, EDU,
   ORG, NET, and GOV are registered by the Internet Registry at the
   InterNIC.  The second level domains in the MIL are registered by the
   DDN registry at NIC.DDN.MIL.  Second level names in INT are
   registered by the PVM at ISI.EDU.

   While all requests for new top-level domains must be sent to the
   Internic (at [e-mail]), the regional registries are
   often enlisted to assist in the administration of the DNS, especially
   in solving problems with a country administration.  Currently, the
   RIPE NCC is the regional registry for Europe and the APNIC is the



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RFC 1591      Domain Name System Structure and Delegation     March 1994


   regional registry for the Asia-Pacific region, while the INTERNIC
   administers the North America region, and all the as yet undelegated
   regions.

      The contact mailboxes for these regional registries are:

         INTERNIC        [e-mail]
         APNIC           [e-mail]
         RIPE NCC        [e-mail]

   The policy concerns involved when a new top-level domain is
   established are described in the following.  Also mentioned are
   concerns raised when it is necessary to change the delegation of an
   established domain from one party to another.

   A new top-level domain is usually created and its management
   delegated to a "designated manager" all at once.

   Most of these same concerns are relevant when a sub-domain is
   delegated and in general the principles described here apply
   recursively to all delegations of the Internet DNS name space.

   The major concern in selecting a designated manager for a domain is
   that it be able to carry out the necessary responsibilities, and have