A sort-of information leak showing the link between IPv4 and IPv6 addresses (if you had any hope the link between those might be a secret):Jul 8 15:15:25 abaris named[5327]: client 2001:470:xxxx:xxxx::2#33086: received notify for zone 'ckts.info' Jul 8 15:15:25 abaris named[5327]: zone ckts.info/IN: refused notify from non-master: 2001:470:xxxx:xxxx::2#33086 Jul 8 15:15:25 abaris named[5327]: client 68.178.91.34#33085: received notify for zone 'ckts.info' Jul 8 15:15:25 abaris named[5327]: zone ckts.info/IN: refused notify from non-master: 68.178.91.34#33085Timing and portnumbers make it quite visible that those addresses are in use by the same machine. Other protocols can probably give the same results, for example with http and cookies I could link IPv4 and IPv6 addresses.A problem? Not to me. Privacy by obscurity? Don't expect it.