The DNS64 code was written by Viagenie, 2009, by Simon Perrault as part
of the Ecdysis project.  The code is copyright by them, and has the BSD
license (see the dns64/dns64.c file).

To enable DNS64 functionality in Unbound, two directives in unbound.conf must
be edited:

1. The "module-config" directive must start with "dns64". For example:

    module-config: "dns64 validator iterator"

If you're not using DNSSEC then you may remove "validator".

2. The "dns64-prefix" directive indicates your DNS64 prefix. For example:

    dns64-prefix: 64:FF9B::/96

The prefix must be a /96 or shorter.

To test that things are working right, perform a query against Unbound for a
domain name for which no AAAA record exists. You should see a AAAA record in
the answer section. The corresponding IPv6 address will be inside the DNS64
prefix. For example:

    $ unbound -c unbound.conf
    $ dig @localhost jazz-v4.viagenie.ca aaaa
    [...]
    ;; ANSWER SECTION:
    jazz-v4.viagenie.ca.        86400   IN      AAAA    64:ff9b::ce7b:1f02