There's a bug in the ReverseMap.fromAddress(String) method that always does IPv4 lookups.
This makes the Java dig implementation to fail for IPv6 reverse lookups.
The patch attached checks for an IPv6 address (':' in address) and creates a correctly typed Address object from the address.
Unified Diff against dnsjava 2.0.6
This is definitely a bug. I fixed the code to work, by attempting to parse the String as both an IPv4 and IPv6 address.
Ticket moved from /p/dnsjava/patches/12/