I have 3 internal dns servers forwarding to my external DNS servers. Split brain on the internal DNS. when a client does an nslookup to the internal servers the servers are timing out if the query is asked with any upper case letters in the query. but works if the query is in lower case. example GOOD.com will respond with DNS request timed out. timeout was 2 seconds. Then immediately after if lookup good.com the non-authoritative answer comes back to me. Then if I do another lookup right away with GOOD.com it comes back with an answer. If I clear the cache on the DNS server, a lookup to GOOD.com will fail once again. This is happening to all of my internal DNS servers. We are using forwarders to my external DNS servers and we are using recursion on the servers. I'm hoping this is just a configuration issue.
Thanks for any help with this.