error sending response: host unreachable, RHEL4 under Ensim Pro 10.3.0 Options

[DragonSmoke]

My servers been a bit slow as of late. Some of my sites are even timing out, as least ones using MySQL. I have checked and updated MySQL, but it didn't seem to help. I went over my LogWatch files and low and behold I am getting tons of requests from Named:

**Unmatched Entries**
client 66.230.128.15 error sending response: host unreachable: 892 Time(s)
client 66.230.160.1 error sending response: host unreachable: 1230 Time(s)
client 69.50.142.11 error sending response: host unreachable: 13 Time(s)
client 69.50.142.110 error sending response: host unreachable: 5 Time(s)
client 76.9.16.171 error sending response: host unreachable: 183 Time(s)
notify question section contains no SOA: 1 Time(s)

These are obviously causing some issues. I have gone through some forums here and elsewhere in an effort to find a solution, but am coming up blank.

I digged these domains direct from my box and they all came back with a reply, so I don't think it's an issue with firewall (although could be wrong). I have also Googled the IP's and noticed that they are not favored domains.

I do host my own DNS server, and my resolv.conf is such:

nameserver 127.0.0.1
nameserver 207.218.192.38
nameserver 207.218.192.39

Any help would be grateful.

update: 25 JAN 09

I have since updated my server to Parallels 10.3.2, won't let me upgrade to 10.3.3, something about license file. License does show as valid though. This upgrade did not resolve DoS issues, something many servers are subject to, but Parallels doesn't address in their software.

What I need to know is how to disable recursive DNS lookups on an Ensim box. I do run my own DNS off this server, but according to SANS I should have recursive DNS to prevent the attacks that I am receiving. I also need to know what other security software I should install to prevent these attacks.