If you are running your own nameservers and you have checked your DNS report at dnsreport (or the non-pay site I recommend IntoDNS you’re probably seeing Fail Open DNS Servers. You should probably (in the interest of Server Security) close the open DNS servers.How do I check my system?
Go to www.dnsreport.com or IntoDNS and enter your domain name, eg MYSITE.com
You’re safe if you see: PASS Open DNS servers
You need to do the steps in this tutorial if you see: FAIL Open DNS servers
Closing Open DNS Servers Tutorial