Check root hints unbound
Are we auto-updating the root hints once in a while? If not: they change once in a while.
The current IP addresses for the L.ROOT-SERVERS.NET service are:
199.7.83.42
2001:500:3::42
As of March 23, 2016, the new IP addresses for the L.ROOT-SERVERS.NET service will be:
199.7.83.42
2001:500:9f::42
https://www.internic.net/domain/named.cache http://www.internic.net/domain/named.cache
(from redmine: created on 2016-03-10)