I have built a new Ubuntu 10.4 server this weekend to host my Zimbra server on so have setup split DNS.
From what I can tell, it's all fine. I can do an nslook up and get results. Can send and receive emails but keep getting wierd ossec messages like below which has nothing to do with email we send. Hoping someone can advise.
OSSEC HIDS Notification.
2012 Jul 15 10:57:01
Received From: mail->/var/log/syslog
Rule: 1002 fired (level 2) -> "Unknown problem somewhere in the system."
Portion of the log(s):
Jul 15 10:56:59 mail named: error (network unreachable) resolving '18.104.22.168.zen.spamhaus.org/A/IN': 2001:7b8:3:1f:0:2:53:2#53