If you want to make sure that the iptables rules only blocks traffic from the master server. Then you can add this to the iptables rule:
Code:
-s cod2master.activision.com
The hostname will be resolved before the rule is submitted to the kernel. According to linux man, it is a bad idea to add a name that needs to be resolved with a remote query. So you could replace cod2master.activision with 63.146.124.40.