[ netinfo/hostserver-instructions.txt ]				[ 5/90 VN]

The NIC Internet Hostname Server is a TCP-based host information
program and protocol running on the NIC.DDN.MIL machine.  The
function of this particular server is to deliver machine-readable
name/address information describing the networks, gateways, hosts, and
domains within the internet environment.  Basic use of the NIC
Hostname Server is documented in RFC 953, which is available via FTP
from NIC.DDN.MIL as the file RFC:RFC953.TXT.

To access this server from a program, establish a TCP connection to
port 101 (decimal) at the service host, NIC.DDN.MIL (192.67.67.20).
Send the information request (a single line), and read the resulting
response.  The connection is closed by the server upon completion of
the response, so only one request can be made for each connection.

For example:

     From Remote Host:  telnet NIC.DDN.MIL 101<Return>
                        haddr 192.67.67.20<Return>

SRI-NIC response:
     HOST : 192.67.67.20 : NIC.DDN.MIL : DEC-2060 : TCP/TELNET, 
     TCP/SMTP, TCP/TIME, TCP/FTP, TCP/ECHO, ICMP, UDP/TIME, UDP/DOMAIN,
     TCP/FINGER:

     Connection closed by foreign host

The currently supported keywords are:

Keyword         Response
-------         --------
HELP            This info
VERSION         "VERSION: <string>" where <string> will be different
                        for each version of the host table.
HNAME <hostname> One or more matching host table entries.
HADDR <hostaddr> One or more matching host table entries.
ALL             The entire host table.
ALL-Z           The entire host table in Unix COMPRESS format.
ALL-MIL         A host table of MILNET sites only.

DOMAINS         The entire top-level domain table (domains only).
ALL-DOM         Both the entire domain table and the host table.

ALL-NETS        Just the NETWORK section of the host table.

The server accepts only a single command line and returns only a
single response before closing the connection.  HNAME and HADDR are
useful for looking up a specific host by name or address; VERSION can
be used by automated processes to see whether a "new" version of the
host table exists without having to transfer the whole table.  Note,
however, that the returned version string is only guaranteed to be
unique to each version, and nothing should currently be assumed about
its format.

PLEASE NOTE: the Official DoD Internet Host Table is updated twice a
week.  HNAME or HADDR may return information that is not yet
incorporated into the latest host table.  Use VERSION number instead
to verify whether you have the latest host table information.

Problems, complaints, or suggestions should be sent via electronic
mail to HOSTMASTER@NIC.DDN.MIL.