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 (26.0.0.73 or 10.0.0.51), 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.
host table described herein each address is represented by four decimal numbers separated by a period. Each decimal number represents 1 octet.
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| +-----+--------+--------------+--------------+--------------+
+-+------------+--------------+--------------+--------------+ |0| 10 or 26 | HOST | LOGICAL HOST | PSN (IMP) | +-+------------+--------------+--------------+--------------+
(NOTE: RFC-796 also describes the local address mappings for several other networks.)
before being used and before traffic is passed by a DoD host. Names and addresses for domains and networks are to be registered with the DDN Network Information Center (HOSTMASTER@SRI-NIC.ARPA) or 800-235-3155.
The NIC will attempt to keep similar information for non-DoD networks and hosts, if this information is provided, and as long as it is needed, i.e., until intercommunicating network name servers are in place.
NET : 10.0.0.0 : ARPANET :
NET : 128.10.0.0 : PURDUE-CS-NET :
GATEWAY : 10.0.0.77, 18.10.0.4 : MIT-GW.ARPA,MIT-GATEWAY : PDP-11 :
MOS : IP/GW,EGP :
HOST : 26.0.0.73, 10.0.0.51 : SRI-NIC.ARPA,SRI-NIC,NIC : DEC-2060 :
TOPS20 :TCP/TELNET,TCP/SMTP,TCP/TIME,TCP/FTP,TCP/ECHO,ICMP :
HOST : 10.2.0.11 : SU-TAC.ARPA,SU-TAC : C/30 : TAC : TCP :
; (semicolon) is used to denote the beginning of a comment. Any text on a given line following a ';' is a comment, and not part of the host table. NET keyword introducing a network entry GATEWAY keyword introducing a gateway entry HOST keyword introducing a host entry DOMAIN keyword introducing a domain entry :(colon) is used as a field delimiter ::(2 colons) indicates a null field ,(comma) is used as a data element delimiter XXX/YYY indicates protocol information of the type TRANSPORT/SERVICE.
where TRANSPORT/SERVICE options are specified as
"FOO/BAR" both transport and service known
"FOO" transport known; services not known "BAR" service is known, transport not known
NOTE: See "Assigned Numbers" for specific options and acronyms for machine types, operating systems, and protocol/services.
Each host table entry is an ASCII text string comprised of 6 fields, where
Field 1 KEYWORD indicating whether this entry pertains to a NET, GATEWAY, HOST, or DOMAIN. NET entries are assigned and cannot have alternate addresses or nicknames. DOMAIN entries do not use fields 4, 5, or 6. Field 2 Internet Address of Network, Gateway, or Host followed by alternate addresses. Addresses for a Domain are those where a Domain Name Server exists for that domain. Field 3 Official Name of Network, Gateway, Host, or Domain (with optional nicknames, where permitted). Field 4 Machine Type Field 5 Operating System Field 6 Protocol List
Fields 4, 5 and 6 are optional. For a Domain they are not used.
Fields 3-6, if included, pertain to the first address in Field 2.
'Blanks' (spaces and tabs) are ignored between data elements or fields, but are disallowed within a data element.
Each entry ends with a colon.
The entries in the table are grouped by types in the order Domain, Net, Gateway, and Host. Within each type the ordering is unspecified.
Note that although optional nicknames are allowed for hosts, they are discouraged, except in the case where host names have been changed
and both the new and the old names are maintained for a suitable period of time to effect a smooth transition. Nicknames are not permitted for NET names.
<entry> ::= <keyword> ":" <addresses> ":" <names> [":" [<cputype>] [":" [<opsys>] [":" [<protocol list>] ]]] ":" <addresses> ::= <address> *["," <address>] <address> ::= <octet> "." <octet> "." <octet> "." <octet> <octet> ::= <0 to 255 decimal> <names> ::= <netname> | <gatename> | <domainname> *["," <nicknames>] | <official hostname> *["," <nicknames>] <netname> ::= <name> <gatename> ::= <hname> <domainname> ::= <hname> <official hostname> ::= <hname> <nickname> ::= <hname> <protocol list> ::= <protocol spec> *["," <protocol spec>] <protocol spec> ::= <transport name> "/" <service name> | <raw protocol name>
<entry-field> ::= <entry-text> [<cr><lf> <blank> <entry-field>] <entry-text> ::= <print-char> *<text> <blank> ::= <space-or-tab> [<blank>] <keyword> ::= NET | GATEWAY | HOST | DOMAIN <hname> ::= <name>*["."<name>] <name> ::= <let>[*[<let-or-digit-or-hyphen>]<let-or-digit>] <cputype> ::= PDP-11/70 | DEC-1080 | C/30 | CDC-6400...etc. <opsys> ::= ITS | MULTICS | TOPS20 | UNIX...etc. <transport name> ::= TCP | NCP | UDP | IP...etc. <service name> ::= TELNET | FTP | SMTP | MTP...etc. <raw protocol name> ::= <name> <comment> ::= ";" <text><cr><lf> <text> ::= *[<print-char> | <blank>] <print-char> ::= <any printing char (not space or tab)>
Notes: