dnsjava is an implementation of DNS in Java. It supports almost 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.

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

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

Please use the Github [issue tracker](https://github.com/dnsjava/dnsjava/issues)

and send - well tested - pull requests. The

Some settings of dnsjava can be configured via

[system properties](https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html):

<table>

<thead>

<tr>

<th rowspan="2">Property</th>

<th>Type</th>

<th>Default</th>

<th>Example</th>

</tr>

<tr>

<th colspan="3">Explanation</th>

</tr>

</thead>

<tbody class="rich-diff-level-one">

<tr>

<td rowspan="2">dns.server</td>

<td>String</td>

<td>-</td>

<td>8.8.8.8,[2001:4860:4860::8888]:853,dns.google</td>

</tr>

<tr>

<td colspan="3">DNS server(s) to use for resolving. Comma separated list. Can be IPv4/IPv6 addresses or hostnames (which are resolved using Java's built in DNS support).</td>

</tr>

<tr>

<td rowspan="2">dns.search</td>

<td>String</td>

<td>-</td>

<td>ds.example.com,example.com</td>

</tr>

<tr>

<td colspan="3">Comma separated list of DNS search paths.</td>

</tr>

<tr>

<td rowspan="2">dns.ndots</td>

<td>Integer</td>

<td>1</td>

<td>2</td>

</tr>

<tr>

<td colspan="3">Sets a threshold for the number of dots which must appear in a name given to resolve before an initial absolute query will be made.</td>

</tr>

<tr>

<td rowspan="2">dnsjava.options</td>

<td>option list</td>

<td>-</td>

<td>BINDTTL,tsigfudge=1</td>

</tr>

<tr>

<td colspan="3">Comma separated key-value pairs, see below.</td>

</tr>

<tr>

<td rowspan="2">dnsjava.configprovider.sunjvm.enabled</td>

<td>Boolean</td>

<td>false</td>

<td>true</td>

</tr>

<tr>

<td colspan="3">Set to true to enable the reflection based DNS server lookup, see limitations below.</td>

</tr>

<tr>

<td rowspan="2">dnsjava.udp.ephemeral.start</td>

<td>Integer</td>

<td>49152 (Linux: 32768)</td>

<td>50000</td>

</tr>

<tr>

<td colspan="3">First ephemeral port for UDP-based DNS queries.</td>

</tr>

<tr>

<td rowspan="2">dnsjava.udp.ephemeral.end</td>

<td>Integer</td>

<td>65535 (Linux: 60999)</td>

<td>60000</td>

</tr>

<tr>

<td colspan="3">Last ephemeral port for UDP-based DNS queries.</td>

</tr>

<tr>

<td rowspan="2">dnsjava.udp.ephemeral.use_ephemeral_port</td>

<td>Boolean</td>

<td>false</td>

<td>true</td>

</tr>

<tr>

<td colspan="3">Use an OS-assigned ephemeral port for UDP queries. Enabling this option is insecure! Do NOT use it.</td>

</tr>

</tbody>

</table>

The dnsjava.options configuration options can also be set programmatically

through the `Options` class. Please refer to the Javadoc for details.

| Key | Type | Default | Explanation |

| --- | ---- | -------| ----------- |

| BINDTTL | Boolean | false | Print TTLs in BIND format |

| multiline | Boolean | false | Print records in multiline format |

| noPrintIN | Boolean | false | Don't print the class of a record if it's IN |

| tsigfudge | Integer | 300 | Sets the default TSIG fudge value (in seconds) |

| sig0validity | Integer | 300 | Sets the default SIG(0) validity period (in seconds) |

dnsjava comes with several built-in resolvers:

- `SimpleResolver`: a basic resolver that uses UDP by default and falls back

to TCP if required.

- `ExtendedResolver`: a resolver that uses multiple `SimpleResolver`s to send

the queries. Can be configured to query the servers in a round-robin order.

Blacklists a server if it times out.

- `DohResolver`: a very basic DNS over HTTP resolver, e.g. to use

`https://dns.google/query`.

The project [dnssecjava](https://github.com/ibauersachs/dnssecjava) has a

resolver that validates responses with DNSSEC.

dnsjava 3 has significant API changes compared to version 2.1.x and is

neither source nor binary compatible. The most important changes are:

- The minimum supported version is Java 8

- Uses [slf4j](http://www.slf4j.org/) for logging and thus needs `slf4j-api`

on the classpath

- The [command line tools](USAGE.md) were moved to the `org.xbill.DNS.tools`

package

- On Windows, [JNA](https://github.com/java-native-access/jna) should be

on the classpath for the search path

- The `Resolver` API for custom resolvers has changed to use

`CompletionStage<Message>` for asynchronous resolving. The built-in

resolvers are now fully non-blocking and do not start a thread per

query anymore.

- Many methods return a `List<T>` instead of an array. Ideally, use a

for-each loop. If this isn't possible, call `size()` instead of

using `length`:

- Cache#findAnyRecords

- Cache#findRecords

- Lookup#getDefaultSearchPath

- Message#getSectionRRsets

- SetResponse#answers

- ResolverConfig

- RRset returns a List<T> instead of an `Iterator`. Ideally, modify your

code to use a for-each loop. If this is not possible, create an iterator

on the returned list:

- RRset#rrs

- RRset#sigs

- Methods using `java.util.Date` are deprecated. Use the new versions with

`java.time.Instant` or `java.time.Duration` instead

- The type hierarchy of `SMIMEARecord` changed, it now inherits from

`TLSARecord` and constants are shared

- `Record`s are no longer marked as `Serializable`. Use the RFC defined

serialization formats:

- `toString()`, `rrToString()` <-> `fromString()`

- `toWire()` <-> `fromWire()`, `newRecord()`

- `Message` and `Header` properly supported `clone()`

Java versions from 1.4 to 8 can load DNS service providers at runtime. The

To load the dnsjava service provider, build dnsjava on JDK 8 and set the system property:

Run `mvn package` from the toplevel directory to build dnsjava. JDK 8

or higher is required.

[Matt Rutherford](mailto:rutherfo@cs.colorado.edu) 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`.

path is at runtime from within the JVM. dnsjava attempts several methods

checked. The servers can either be IP addresses or hostnames (which are

- On Unix/Solaris, `/etc/resolv.conf` is parsed.

- On Windows, if [JNA](https://github.com/java-native-access/jna) is available

on the classpath, the `GetAdaptersAddresses` API is used.

- On Android, depending on the SDK level, either the properties `net.dns[1234]`

or the `ConnectivityManager` is used (requires initialization).

- The `sun.net.dns.ResolverConfiguration` class is queried if enabled.

- If available and no servers have been found yet,

[JNDI-DNS](https://docs.oracle.com/javase/8/docs/technotes/guides/jndi/jndi-dns.html) is used.

- Brian Wellington (@bwelling), March 12, 2004

- Various contributors, see [Changelog](Changelog)

- Ingo Bauersachs (@ibauersachs), current maintainer