6bf1f57fc1
if a nameserver does not respond, we flag it in the database (available = False) and stop talking to it for 5 minutes. after 5 minutes, we flag it available = True again and retry talking to it (and if not successful, flag it as unavailable again). this avoids a unresponsive UI as we do a lot of ns queries from the templates to get v4 and v6 addresses of our hosts from master nameservers. we log a warning when setting unavailable and a info when setting available.