RFC 882 (rfc882) - Page 1 of 31


Domain names: Concepts and facilities



Alternative Format: Original Text Document



Network Working Group                                     P. Mockapetris
Request for Comments:  882                                           ISI
                                                           November 1983

                 DOMAIN NAMES - CONCEPTS and FACILITIES

        +-----------------------------------------------------+
        |                                                     |
        | This RFC introduces domain style names, their use   |
        | for ARPA Internet mail and host address support,    |
        | and the protocols and servers used to implement     |
        | domain name facilities.                             |
        |                                                     |
        | This memo describes the conceptual framework of the |
        | domain system and some uses, but it omits many      |
        | uses, fields, and implementation details.  A        |
        | complete specification of formats, timeouts, etc.   |
        | is presented in RFC 883, "Domain Names -            |
        | Implementation and Specification".  That RFC        |
        | assumes that the reader is familiar with the        |
        | concepts discussed in this memo.                    |
        |                                                     |
        +-----------------------------------------------------+

INTRODUCTION

   The need for domain names

      As applications grow to span multiple hosts, then networks, and
      finally internets, these applications must also span multiple
      administrative boundaries and related methods of operation
      (protocols, data formats, etc).  The number of resources (for
      example mailboxes), the number of locations for resources, and the
      diversity of such an environment cause formidable problems when we
      wish to create consistent methods for referencing particular
      resources that are similar but scattered throughout the
      environment.

      The ARPA Internet illustrates the size-related problems; it is a
      large system and is likely to grow much larger.  The need to have
      a mapping between host names (e.g., USC-ISIF) and ARPA Internet
      addresses (e.g., 10.2.0.52) is beginning to stress the existing
      mechanisms.  Currently hosts in the ARPA Internet are registered
      with the Network Information Center (NIC) and listed in a global
      table (available as the file HOSTS.TXT on the SRI-NIC
      host) [1].  The size of this table, and especially the frequency
      of updates to the table are near the limit of manageability.  What
      is needed is a distributed database that performs the same
      function, and hence avoids the problems caused by a centralized
      database.

      The problem for computer mail is more severe.  While mail system
      implementers long ago recognized the impossibility of centralizing


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