Ken Harrenstien RFC-811
Vic White 1 March 1982
Elizabeth Feinler
Network Information Center
SRI International
 HOSTNAMES SERVER
INTRODUCTION
 The NIC Internet Hostnames Server is an NCP/TCP-based host
 information program and protocol running on the SRI-NIC
 machine. It is one of a series of ARPANET/Internet name
 services maintained by the Network Information Center (NIC) at
 SRI International on behalf of the Defense Communications
 Agency (DCA). The function of this particular server is to
 deliver machine-readable name/address information describing
 networks, gateways, hosts, and eventually domains, within the
 internet environment. As currently implemented, the server
 provides the information outlined in the DoD Internet Host
 Table Specification (RFC 810).
QUERY/RESPONSE FORMAT
 The name server accepts simple text query requests of the form
 <command key> <argument(s)> [<options>]
 where square brackets ("[]") indicate an optional field. The
 command key is a keyword indicating the nature of the request.
 The defined keys are explained below.
 The response, on the other hand, is of the form
 <response key> : <rest of response>
 where <response key> is a keyword indicating the nature of the
 response, and the rest of the response is interpreted in the
 context of the key.
COMMAND/RESPONSE KEYS
 The currently defined keywords are:
 Command Keys:
 HNAME (find entry with given name)
 HADDR (find entry with given address)
 ALL (return entire host table)
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RFC 811 Hostnames Server
 Response Keys:
 ERR (entry not found, nature of error follows)
 NET (entry found, rest of entry follows)
 GATEWAY (entry found, rest of entry follows)
 HOST (entry found, rest of entry follows)
 BEGIN (followed by multiple entries)
 END (done with BEGIN block of entries)
 More keywords will be added as new needs are recognized. A
 more detailed description of the allowed requests/responses
 will follow.
PROTOCOL
 To access this server from a program, connect to service host
 (SRI-NIC)
 TCP: port 101 decimal
 NCP: socket 101 decimal for ICP
 send the information query, and await the response.
 Note: Care should be taken to interpret the nature of the
 reply (e.g, single record or multiple record), so that no
 confusion about the state of the reply results. An "ALL"
 request will likely return several hundred or more records of
 all types (see RFC 810), whereas "HNAME" or "HADDR" will
 usually return one HOST record, or "BEGIN:", list of host
 records, "END:", if there is more than one match.
QUERY/RESPONSE EXAMPLES
 1. HNAME Query - Given a name, find the entry or entries that
 match
 the name. For example:
 HNAME SRI-NIC <CRLF> ;where <CRLF> is a carriage
 return/
 linefeed, and 'SRI-NIC' is a
 host name
 The likely response is:
 HOST : 10.0.0.73 : SRI-NIC,NIC : FOONLY-F3 : TENEX : NCP :
 A response may stretch across more than one line.
 Continuation lines always begin with at least one space.
 For example:
 HOST : 10.0.0.73 : SRI-NIC,NIC : FOONLY-F3 : TENEX : NCP :
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Hostnames Server RFC 811
 2. HADDR Query - Given an internet address (as specified in
 RFC
 796) find the entry or entries that match that address.
 For example:
 HADDR 10.0.0.73 <CRLF> ;where <CRLF> is a carriage
 return/
 linefeed, and '10.0.0.73' is a
 host
 address
 The likely response is the same as for the HNAME request:
 HOST : 10.0.0.73 : SRI-NIC,NIC : FOONLY-F3 : TENEX : NCP :
 3. ALL Query - Deliver the entire internet host table in a
 machine-readable form. For example:
 ALL <CRLF> ;where <CRLF> is a carriage return/linefeed
 The likely response is the keyword 'BEGIN' followed by a
 colon ':', followed by the entire internet host table in
 the format specified in RFC 810, followed by 'END:'. For
 example:
 BEGIN:
 NET : 10.0.0.0 : ARPANET :
 NET : 18.0.0.0 : LCSNET :
 GATEWAY : 10.0.0.77, 18.8.0.4 : MIT-GW :: MOS : IP/GW :
 HOST : 10.0.0.73 : SRI-NIC,NIC : TENEX : FOONLY-F3
 NCP/TELNET, NCP/FTP, TCP :
 HOST : 10.2.0.11 : SU-TIP, FELT-TIP ::
 END:
ERROR HANDLING
 1. ERR Reply - may occur on any query, and should be permitted
 in
 any access program using the name server. Errors are of
 the form
 ERR : <code> : <string> :
 as in
 ERR : NAMNFD : Name not found :
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RFC 811 Hostnames Server
 The error code is a unique descriptor, limited to 8 characters
 in length for any given error. It may be used by the access
 program to identify the error and, in some cases, to handle it
 automatically. The string is an accompanying message for a
 given error for that case where the access program simply logs
 the error message. Current codes and their associated
 interpretations are
 NAMNFD -- Name not found; name not in table
 ADRNFD -- Address not found; address not in
 table
 ILLCOM -- Illegal command; command key not
 recognized
 TMPSYS -- Temporary system failure, try again
 later
REMARKS
 The host name server described above runs over a single global
 internet host name/address data base. This data base is an
 extension of the old ARPANET Hosts.txt file, and is being
 maintained by the NIC to provide continuity during the
 transition and expansion to the internet environment. We view
 the central administration of a global host name data base,
 along with this simple name server, as an interim solution on
 the way to a decentralized, distributed name/address
 translation service. The NIC welcomes your comments and
 suggestions for such an expanded service. Send comments to
 NIC@SRI-NIC.
REFERENCES
 1. Feinler, E., Harrenstien, K., Su, Z. and White, V.
 Official
 DoD Internet Host Table Specification, RFC 810, Network
 Information Center, SRI International, March 1, 1982.
 2. Postel, J. Address Mappings, RFC 796, Information Sciences
 Inst., Univ. of Southern Calif., Marina Del Rey, Sept.
 1981.
 3. Pickens, J., Feinler, E., and Mathis, J. The NIC Name
 Server,
 A Datagram-based Information Utility, Network Information
 Center, SRI International, July 1979.