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 hostmaster@internic.net), 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        hostmaster@internic.net

         APNIC           hostmaster@apnic.net

         RIPE NCC        ncc@ripe.net

   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

   the ability to do a equitable, just, honest, and competent job.

   1) The key requirement is that for each domain there be a designated

      manager for supervising that domain's name space.  In the case of

      top-level domains that are country codes this means that there is

      a manager that supervises the domain names and operates the domain

      name system in that country.

      The manager must, of course, be on the Internet.  There must be

      Internet Protocol (IP) connectivity to the nameservers and email

      connectivity to the management and staff of the manager.

      There must be an administrative contact and a technical contact

      for each domain.  For top-level domains that are country codes at

      least the administrative contact must reside in the country

      involved.

   2) These designated authorities are trustees for the delegated

      domain, and have a duty to serve the community.

      The designated manager is the trustee of the top-level domain for

      both the nation, in the case of a country code, and the global

      Internet community.

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RFC 1591      Domain Name System Structure and Delegation     March 1994

      Concerns about "rights" and "ownership" of domains are

      inappropriate.  It is appropriate to be concerned about

      "responsibilities" and "service" to the community.

   3) The designated manager must be equitable to all groups in the

      domain that request domain names.

      This means that the same rules are applied to all requests, all

      requests must be processed in a non-discriminatory fashion, and

      academic and commercial (and other) users are treated on an equal

      basis.  No bias shall be shown regarding requests that may come

      from customers of some other business related to the manager --

      e.g., no preferential service for customers of a particular data

      network provider.  There can be no requirement that a particular

      mail system (or other application), protocol, or product be used.

      There are no requirements on subdomains of top-level domains

      beyond the requirements on higher-level domains themselves.  That

      is, the requirements in this memo are applied recursively.  In

      particular, all subdomains shall be allowed to operate their own

      domain name servers, providing in them whatever information the

      subdomain manager sees fit (as long as it is true and correct).

   4) Significantly interested parties in the domain should agree that

      the designated manager is the appropriate party.

      The IANA tries to have any contending parties reach agreement

      among themselves, and generally takes no action to change things

      unless all the contending parties agree; only in cases where the

      designated manager has substantially mis-behaved would the IANA

      step in.

      However, it is also appropriate for interested parties to have

      some voice in selecting the designated manager.

      There are two cases where the IANA and the central IR may

      establish a new top-level domain and delegate only a portion of

      it: (1) there are contending parties that cannot agree, or (2) the

      applying party may not be able to represent or serve the whole

      country.  The later case sometimes arises when a party outside a

      country is trying to be helpful in getting networking started in a

      country -- this is sometimes called a "proxy" DNS service.

      The Internet DNS Names Review Board (IDNB), a committee

      established by the IANA, will act as a review panel for cases in

      which the parties can not reach agreement among themselves.  The

      IDNB's decisions will be binding.

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RFC 1591      Domain Name System Structure and Delegation     March 1994

   5) The designated manager must do a satisfactory job of operating the

      DNS service for the domain.

      That is, the actual management of the assigning of domain names,

      delegating subdomains and operating nameservers must be done with

      technical competence.  This includes keeping the central IR (in

      the case of top-level domains) or other higher-level domain

      manager advised of the status of the domain, responding to

      requests in a timely manner, and operating the database with

      accuracy, robustness, and resilience.

      There must be a primary and a secondary nameserver that have IP

      connectivity to the Internet and can be easily checked for

      operational status and database accuracy by the IR and the IANA.

      In cases when there are persistent problems with the proper

      operation of a domain, the delegation may be revoked, and possibly

      delegated to another designated manager.

   6) For any transfer of the designated manager trusteeship from one

      organization to another, the higher-level domain manager (the IANA

      in the case of top-level domains) must receive communications from

      both the old organization and the new organization that assure the

      IANA that the transfer in mutually agreed, and that the new

      organization understands its responsibilities.

      It is also very helpful for the IANA to receive communications

      from other parties that may be concerned or affected by the

      transfer.

4. Rights to Names 

   1) Names and Trademarks

      In case of a dispute between domain name registrants as to the

      rights to a particular name, the registration authority shall have

      no role or responsibility other than to provide the contact

      information to both parties.

      The registration of a domain name does not have any Trademark

      status.  It is up to the requestor to be sure he is not violating

      anyone else's Trademark.

   2) Country Codes

      The IANA is not in the business of deciding what is and what is

      not a country.

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RFC 1591      Domain Name System Structure and Delegation     March 1994

      The selection of the ISO 3166 list as a basis for country code

      top-level domain names was made with the knowledge that ISO has a

      procedure for determining which entities should be and should not

      be on that list.

5. Security Considerations 

   Security issues are not discussed in this memo.

6. Acknowledgements 

   Many people have made comments on draft version of these descriptions

   and procedures.  Steve Goldstein and John Klensin have been

   particularly helpful.

7. Author's Address 

   Jon Postel

   USC/Information Sciences Institute

   4676 Admiralty Way

   Marina del Rey, CA  90292

   Phone: 310-822-1511

   Fax:   310-823-6714

   EMail: Postel@ISI.EDU

7. References 

   [1] Cooper, A., and J. Postel, "The US Domain", RFC 1480,

       USC/Information Sciences Institute, June 1993.

   [2] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1340,

       USC/Information Sciences Institute, July 1992.

   [3] Mockapetris, P., "Domain Names - Concepts and Facilities", STD

       13, RFC 1034, USC/Information Sciences Institute, November 1987.

   [4] Mockapetris, P., "Domain Names - Implementation and

       Specification", STD 13, RFC 1035, USC/Information Sciences

       Institute, November 1987.

   [6] Partridge, C., "Mail Routing and the Domain System", STD 14, RFC

       974, CSNET CIC BBN, January 1986.

   [7] Braden, R., Editor, "Requirements for Internet Hosts --

       Application and Support", STD 3, RFC 1123, Internet Engineering

       Task Force, October 1989.

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