Network Working Group                               K. Harrenstien (SRI)Request for Comments: 953                                 M. Stahl (SRI)Obsoletes:  RFC811                                     E. Feinler (SRI)                                                            October 1985                            HOSTNAME SERVERSTATUS OF THIS MEMO   This RFCis the official specification of the Hostname Server   PRotocol.  This edition of the specification includes minor revisions   to RFC811 which brings it up to date.  Distribution of this memo is   unlimited.INTRODUCTION   The NIC Internet Hostname Server is a TCP-based host information   program and protocol running on the SRI-NIC machine.  It is one of a   series of internet name services maintained by the DDN 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 [See RFC-952].  For a discussion of future developments   see also RFC-921 concerning the Domain Name System.PROTOCOL   To access this server from a program, establish a TCP connection to   port 101 (decimal) at the service host, SRI-NIC.ARPA (26.0.0.73 or   10.0.0.51).  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.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>RFC953                                                     October 1985Hostname Server   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.   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, whereas "HNAME" or   "HADDR" will usually return one HOST record.COMMAND/RESPONSE KEYS   The currently defined command keywords are listed below.  NOTE:   Because the server and the features available will evolve with time,   the HELP command should be used to oBTain the most recent summary of   implemented features, changes, or new commands.      Keyword   Response      HELP      This information.      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-OLD   The entire host table without domain style names.      DOMAINS   The entire top-level domain table (domains only).      ALL-DOM   Both the entire domain table and the host table.      ALL-INGWAY                All known gateways in TENEX/TOPS-20 INTERNET.GATEWAYS                format.   Remember that 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 theRFC953                                                     October 1985Hostname Server   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.   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      DOMAIN    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 follows.QUERY/RESPONSE EXAMPLES   1. HNAME Query - Given a name, find the entry or entries that match   the name.  For example:      HNAME SRI-NIC.ARPA <CRLF>         where <CRLF> is a carriage return/ linefeed, and 'SRI-NIC.ARPA'         is a host name      The likely response is:      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 :      A response may stretch across more than one line.  Continuation      lines always begin with at least one space.   2. HADDR Query - Given an internet address (as specified in RFC796)   find the entry or entries that match that address. For example:      HADDR 26.0.0.73 <CRLF>         where <CRLF> is a carriage return/ linefeed, and '26.0.0.73' is         a host address.      The likely response is the same as for the previous HNAME request.RFC953                                                     October 1985Hostname Server   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-952, followed by 'END:'.ERROR HANDLING   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 :   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 laterREFERENCES   1. Harrenstien, K., Stahl, M., and Feinler, E., "Official DoD      Internet Host Table Specification," RFC-952, DDN Network      Information Center, SRI International, October 1985.   2. Pickens, J., Feinler, E., and Mathis, J., "The NIC Name Server," A      Datagram-based Information Utility, RFC-756, Network Information      Center, SRI International, July 1979.   3. Postel, J., "Address Mappings," RFC-796, Information Sciences      Institute, University of Southern California, Marina del Rey,      September 1981.   4. Postel, J., "Domain Name System Implementation Schedule", RFC-921,      Information Sciences Institute, University of Southern California,      Marina del Rey, October 1984.RFC953                                                     October 1985Hostname Server