Elizabeth Feinler                                         RFC 810
Ken Harrenstien                                      1 March 1982
Zaw-Sing Su                              References: RFC 811, 796
Vic White                                      Obsoletes: RFC 608
Network Information Center
SRI International

              DoD INTERNET HOST TABLE SPECIFICATION



INTRODUCTION

    The ARPANET Official Network Host Table, as outlined in RFC 608, no
   longer suits the needs of the DoD community, nor does it follow a
   format suitable for internetting.  This paper specifies a new host
   table format applicable to both ARPANET and Internet needs.

   In addition to host name to host address translation and selected
   protocol information, we have also included network and gateway name
   to address correspondence, and host operating system information.

   This Host Table is utilized by the DoD Host Name Server maintained by
   the ARPANET Network Information Center (NIC) on behalf of the Defense
   Communications Agency (DCA) (RFC 811).  It obsoletes the host table
   described in RFC 608.

LOCATION OF THE STANDARD DoD ONLINE HOST TABLE

   A machine-translatable ASCII text version of the new DoD Host Table
   is online in the file HOSTS.TXT on the SRI-NIC host.  It can
   be obtained by connecting to host SRI-NIC (10.0.0.73) from your local
   FTP server, logging in as user=ANONYMOUS, password=GUEST, and doing a
   'get' on HOSTS.TXT.  The same table may also be obtained via
   the NIC Host Name Server.

   NOTE:  See Appendix A. for timeframe for cutover.

ASSUMPTIONS

   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), and the
   minus sign (-) and period (.).  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 a letter.  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.  A
   host which is a TIP or a TAC should have  "-TIP" or "-TAC" as part of
   its host name, if it is an ARPANET or DoD host.

   2. Internet Addresses are 32-bit addresses (RFC 796).  In the host
   table described herein each address is represented by four decimal
   numbers separated by a period.  Each decimal number represents 1
   octet.


 

RFC 810                                                     1 March 1982
                                                Host Table Specification
                                                                        
                                                                        
   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) (RFC 796).

   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. For the ARPANET (a Class A network), the NET address is 10
   (decimal) and the LOCAL ADDRESS maps as follows: the second octet
   defines the physical host, the third octet defines the logical host,
   and the fourth defines the IMP.

   +-+-------------+---------------+--------------+---------------+
   |0|     10      |    HOST       | LOGICAL HOST |      IMP      |
   +-+-------------+---------------+--------------+---------------+

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

   6.  It is the responsibility of the user using this host table to