How about monitoring your server with something like Nagios or Icinga
using their DNS plugins? If you don't want to run a full Nagios or
Icinga server, you might want to look at a service such as Pingdom,
which can monitor things for you and send you reports.
But does anybody know of ways I can notify myself should this happen
again?
IMHO, there is nothing nsd-specific. You just use a generic monitoring
framework. I use Icinga <http://www.icinga.org/> but there are many
others.
Like most tools, Icinga accepts the Nagios API so you can use the
Monitoring plugins (former Nagios plugins)
<https://www.monitoring-plugins.org/> I use an unmodified check_dns,
configured that way in Icinga:
define service{
use generic-service
host_name mononoke
service_description DNS4
check_command check_dig!-4 -l eu.org -T SOA -A +dnssec
}
define service{
use generic-service
host_name mononoke
service_description DNS6
check_command check_dig!-6 -l eu.org -T SOA -A +dnssec
}