[CentOS] differences in DNS between boxes

Please refer to my thread "excessive DNS slows httpd" in which I discuss a very slow response from my httpd server on my CentOS box after modifying httpd.config .

I have "solved" the problem by blocking all DNS in iptables on my CentOS box. As it happens, this is not a problem in my present configuration, but it can hardly be considered a good solution. Given that the httpd configurations are essentially identical, it appears that there is a difference between my Feodora box and my CentOS box regarding how and when DNS is handled, at least when originated by httpd.

Suggestions would be most welcome.

Mike.