DoD Internet host table specification
RFC 952

Document Type RFC - Unknown (October 1985; Errata)
Updated by RFC 1123
Obsoletes RFC 810
Last updated 2020-07-29
Stream Legacy stream
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Network Working Group                               K. Harrenstien (SRI)
Request for Comments: 952                                 M. Stahl (SRI)
                                                        E. Feinler (SRI)
Obsoletes:  RFC 810, 608                                    October 1985



   This RFC is the official specification of the format of the Internet
   Host Table.  This edition of the specification includes minor
   revisions to RFC-810 which brings it up to date. Distribution of this
   memo is unlimited.


   The DoD Host Table is utilized by the DoD Hostname Server maintained
   by the DDN Network Information Center (NIC) on behalf of the Defense
   Communications Agency (DCA) [See RFC-953].


   A machine-translatable ASCII text version of the DoD Host Table is
   online in the file NETINFO:HOSTS.TXT on the SRI-NIC host.  It can be
   obtained via FTP from your local host by connecting to host
   SRI-NIC.ARPA ( or, logging in as user =
   ANONYMOUS, password = GUEST, and retrieving the file
   "NETINFO:HOSTS.TXT".  The same table may also be obtained via the NIC
   Hostname Server, as described in RFC-953.  The latter method is
   faster and easier, but requires a user program to make the necessary
   connection to the Name Server.


   1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
   to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
   sign (-), and period (.).  Note that periods are only allowed when
   they serve to delimit components of "domain style names". (See
   RFC-921, "Domain Name System Implementation Schedule", for
   background).  No blank or space characters are permitted as part of a
   name. No distinction is made between upper and lower case.  The first
   character must be an alpha character.  The last character must not be
   a minus sign or period.  A host which serves as a GATEWAY should have
   "-GATEWAY" or "-GW" as part of its name.  Hosts which do not serve as
   Internet gateways should not use "-GATEWAY" and "-GW" as part of
   their names. A host which is a TAC should have "-TAC" as the last
   part of its host name, if it is a DoD host.  Single character names
   or nicknames are not allowed.

   2. Internet Addresses are 32-bit addresses [See RFC-796].  In the

Harrenstien & Stahl & Feinler                                   [Page 1]

RFC 952                                                     October 1985

   host table described herein each address is represented by four
   decimal numbers separated by a period.  Each decimal number
   represents 1 octet.

   3. If the first bit of the first octet of the address is 0 (zero),
   then the next 7 bits of the first octet indicate the network number
   (Class A Address).  If the first two bits are 1,0 (one,zero), then
   the next 14 bits define the net number (Class B Address).  If the
   first 3 bits are 1,1,0 (one,one,zero), then the next 21 bits define
   the net number (Class C Address) [See RFC-943].

      This is depicted in the following diagram:

      |0|  NET <-7-> |         LOCAL ADDRESS <-24->               |

      |1 0|      NET  <-14->        |  LOCAL ADDRESS <-16->       |

      |1 1 0|            NET  <-21->               | LOCAL ADDRESS|

   4. The LOCAL ADDRESS portion of the internet address identifies a
   host within the network specified by the NET portion of the address.

   5. The ARPANET and MILNET are both Class A networks.  The NET portion
   is 10 decimal for ARPANET, 26 decimal for MILNET, and the LOCAL
   ADDRESS maps as follows: the second octet identifies the physical
   host, the third octet identifies the logical host, and the fourth
   identifies the Packet Switching Node (PSN), formerly known as an
   Interface Message Processor (IMP).

      |0|  10 or 26  |    HOST      | LOGICAL HOST |   PSN (IMP)  |

      (NOTE:  RFC-796 also describes the local address mappings for
      several other networks.)

   6. It is the responsibility of the users of this host table to
   translate it into whatever format is needed for their purposes.

   7. Names and addresses for DoD hosts and gateways will be negotiated
   and registered with the DDN PMO, and subsequently with the NIC,

Harrenstien & Stahl & Feinler                                   [Page 2]
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