Hi there,
I'm currently investigating one of my Nameservers behvaviour. Recently I switched from a pure virtual setup, to having 3 physical machines, each connected to their own router. Each machine is installed with NetBSD 6.1.5 (Generic) amd64, bind-9.10.1pl1 and exabgp-3.3.2nb1.
The setup is such that bind is listening on aliases bound to lo0 and 127.0.0.1. Exabgp announces the 3 IP adresses with different local_pref for each for the machines, to ensure that all servers are accessible at any given time should one of the physical servers fail in any way, or if bind gives up on resolving things. ExaBGP takes good care of this and that particular part is running quite well.
Now, for 1 of the 3 physical servers, Bind ends up in "parked" state after a while. There seems to be little to no explanation why. At first I thought this was due to a hardware error, so I replaced the hardware. The new hardware did exactly the same.
From what I can read about the "parked" state is that it is currently waiting for some resource, and will not move on, all signals apart from "SIGKILL" will be queued and this is also the behaviour I see, /etc/rc.d/named9 restart takes forever as it is waiting for bind's pid to end. After a kill, it starts up nicely again - runs for a while, then dies.
Currently I've put in a rather ugly hack combining sudo, kill from exabgp. Restarting of named from crontab every 15 minutes, and that "works"(ish).