I noticed an error on all my secondary bind9 servers running on ubuntu linux. This error was appearing in the daemon.log file in /var/log
zone 4playgames.local/IN: refresh: unexpected rcode (SERVFAIL) from master 192.168.10.2#53 (source 0.0.0.0#0)
On the primary DNS server I was recieving this error message in daemon.log:
zone 4playgames.local/IN: loading from master file 4playgames.local.zone failed: CNAME and other data
The primary DNS server was still functioning correctly, however this one zone file was no longer functioning. What caused the problem was there were 2 records that had the same name. A "CNAME" and an "A" record both had the same name in the zone file, which caused the entire zone file not to load anymore.