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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

[]

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

:

where 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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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 ;where 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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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 ;where 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 ;where 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 : : :

as in

ERR : NAMNFD : Name not found :




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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.







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