GNU adns

Advanced, easy to use, asynchronous-capable DNS client library and utilities.

adns is a resolver library for C (and C++) programs, and a collection of useful DNS resolver utilities.

C library

In contrast with the standard interfaces, gethostbyname et al and libresolv, it has the following features:

DNS utility programs

adns also comes with a number of utility programs for use from the command line and in scripts:


I'm afraid there is no manual yet. However, competent C programmers should be able to use the library based on the commented adns.h header file, and the usage messages for the programs should be sufficient.


I'd be pleased if you would let me know if you're using my library in your project, and what you think of it.

If you are subscribed to adns-discuss please send feedback, including bug reports, there; otherwise send mail to If you'd prefer that your message wasn't forwarded to the adns-bugreports list, send it to


I have set up mailinglists adns-announce and adns-discuss. The announcements list is moderated and will contain only announcements of important bugs, new versions, etc. The bug reports address mentioned above is also a mailing list; feel free to subscribe to it.

There are archives and subscription web pages, or you can subscribe by sending mail containing the word `subscribe' to or


Available for download from are: adns is also available from the GNU Project FTP servers and their mirrors.

Technical note

adns requires a real nameserver like BIND or Dents running on the same system or a nearby one, which must be willing to provide `recursive service'. I.e., adns is a `stub resolver'. All properly configured UN*X and GNU systems will already have such nameserver(s); they are usually listed in /etc/resolv.conf.

Copyright and licensing

adns is Copyright 1997-2000 Ian Jackson, Copyright 1999-2000 Tony Finch, and Copyright (C) 1991 Massachusetts Institute of Technology.

adns is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program and documentation is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with adns, or one should be available above; if not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA, or email

Ian Jackson /; more free software by me.

GNU home page; chiark home page; site or mirror home page

This web page is Copyright (C)1996-2000 Ian Jackson. See the Copyright/acknowledgements.

Use any browser - Campaign for a non-browser-specific WWW