DNS server, in erlang.
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Erlang DNS Server

Serve DNS authoritative responses...with Erlang.

Build Status


To build clean:


If you've already built once and just want to recompile the erl-dns source:

./rebar compile


Zones are loaded from JSON.

Example JSON files are in the priv/ directory.

You can also write new systems to load zones by writing the zones directly to the zone cache using erldns_zone_cache:put_zone/1.


An example configuration file can be found in erldns.config.example.

Copy it to erldns.config and modify as needed.


Launch directly:

erl -config erldns.config -pa ebin -pa deps/**/ebin -s erldns

Or use Foreman:

foreman start


Here are some queries to try:

dig -p8053 @ example.com a
dig -p8053 @ example.com cname
dig -p8053 @ example.com ns
dig -p8053 @ example.com mx
dig -p8053 @ example.com spf
dig -p8053 @ example.com txt
dig -p8053 @ example.com sshfp
dig -p8053 @ example.com soa
dig -p8053 @ example.com naptr

dig -p8053 @ -x ptr


In our environment (DNSimple) we are seeing 30 to 65 µs handoff times to retreive a packet from the UDP port and give it to a worker for processing. Your performance may vary, but given those measurements erl-dns is capable of handling between 15k and 30k questions per second. Please note: You may need to configure the number of workers available to handle traffic at higher volumes.


The erldns_resolver module will attempt to find zone data in the zone cache. If you're embedding erl-dns in your application the easiest thing to do is to load the zone cache once the zone cache gen_server starts push an updated zone into the cache each time data changes.

To insert a zone, use erldns_zone_cache:put_zone({Name, Records}) where Name is a binary term such as <<"example.com">> and Records is a list of dns_rr records (whose definitions can be found in deps/dns/include/dns_records.hrl). The name of each record must be the fully qualified domain name (including the zone part).

Here's an example:

  <<"example.com">>, [
      name = <<"example.com">>,
      type = ?DNS_TYPE_A,
      ttl = 3600,
      data = #dns_rrdata_a{ip = {1,2,3,4}}
      name = <<"www.example.com">>,
      type = ?DNS_TYPE_CNAME,
      ttl = 3600,
      data = #dns_rrdata_cname{dname = <<"example.com">>}


Folsom is used to gather runtime metrics and statistics.

There is an HTTP API for querying metric data available at https://github.com/aetrion/erldns-metrics


There is a administrative API for querying the current zone cache and for basic control. You can find it in https://github.com/aetrion/erldns-admin