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The offical home of dnsjava - an implementation of the DNS protocol in Java.
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dnsjava is an implementation of DNS in Java. It supports all defined record types (including the DNSSEC types), and unknown types. It can be used for queries, zone transfers, and dynamic updates. It includes a cache which can be used by clients, and an authoritative only server. It supports TSIG authenticated messages, partial DNSSEC verification, and EDNS0. It is fully thread safe. It can be used to replace the native DNS support in Java.

dnsjava was started as an excuse to learn Java. It was useful for testing new features in BIND without rewriting the C resolver. It was then cleaned up and extended in order to be used as a testing framework for DNS interoperability testing. The high level API and caching resolver were added to make it useful to a wider audience. The authoritative only server was added as proof of concept.

dnsjava on Github

This repository has been a mirror of the dnsjava project at Sourceforge since 2014 to maintain the Maven build for publishing to Maven Central. As of 2019-05-15, Github is officially the new home of dnsjava.

Please use the Github issue tracker and send - well tested - pull requests. The mailing list still exists.


  • Brian Wellington (@bwelling), March 12, 2004
  • Various contributors, see Changelog

Getting started

Run mvn package from the toplevel directory to build dnsjava. JDK 1.4 or higher is required.

Replacing the standard Java DNS functionality:

Java versions from 1.4 to 1.8 can load DNS service providers at runtime. The functionality was removed in JDK 9, a replacement is requested, but so far has not been implemented.

To load the dnsjava service provider, build dnsjava on a JDK that still supports the SPI and set the system property:,dnsjava

This instructs the JVM to use the dnsjava service provide for DNS at the highest priority.

Testing dnsjava

Matt Rutherford contributed a number of unit tests, which are in the tests subdirectory. The hierarchy under tests mirrors the org.xbill.DNS classes. To run the unit tests, execute mvn test. The tests require JUnit.

Some high-level test programs are in org/xbill/DNS/tests.


There's no standard way to determine what the local nameserver or DNS search path is at runtime from within the JVM. dnsjava attempts several methods until one succeeds.

  • The properties dns.server and (comma delimited lists) are checked. The servers can either be IP addresses or hostnames (which are resolved using Java's built in DNS support).
  • The class is queried.
  • On Unix, /etc/resolv.conf is parsed.
  • On Windows, ipconfig/winipcfg is called and its output parsed. This may fail for non-English versions on Windows.
  • As a last resort, localhost is used as the nameserver, and the search path is empty.

The underlying platform must use an ASCII encoding of characters. This means that dnsjava will not work on OS/390, for example.

Additional documentation

Javadoc documentation can be built with mvn javadoc:javadoc or viewed online at See the examples for some basic usage information.


dnsjava is placed under the BSD license. Several files are also under additional licenses; see the individual files for details.

Final notes

  • Thanks to Network Associates, Inc. for sponsoring some of the original dnsjava work in 1999-2000.
  • Thanks to Nominum, Inc. for sponsoring some work on dnsjava from 2000 through 2017.
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