Answer as to the direct cause (posted to that question): "We recently relocated our NY datacenter, and therefore all the IPs in NY changed. We didn't update t

Answer as to the direct cause (posted to that question): "We recently relocated our NY datacenter, and therefore all the IPs in NY changed. We didn't update to the new IP for the master DNS server (in both the named.conf and the zone files), and therefore all of our slaves hit our expiry time (one week). This is fixed now, so things should start coming back up."