Round Robbin DNS and Windows Hosts file

I am trying to block all but 1 user from MSN chat (msn live or whatever it's called now). My plan is to point the DNS to 127.0.0.1. However one user has to have it, I can edit the host file and put in the ip address to over ride the network DNS. However MSN uses round robin DNS and I don't want to have it go down when they change servers. Does someone have a better idea on how to do this? or how to do round robin DNS in a host file?

From serverfault lineman60

• You could just leave DNS alone and block the IP's at the router.

  Then use a DHCP reservation to give your one persion the same IP address each time, and allow that one to go through.

  Way easier to manage (few changes in 1 place). Little easier to troubleshoot in the future, plus a savvy user might just update his/her hosts file to get to MSN.

  Not sure if you mean msn communicator/chat or the www.msn.com... If it's the chat protocol, block the msn ports (do some searching) and you don't have to worry about IP's in the future...

  lineman60 : blocking ports are not an option, MSN chat can go out over port 80 http://support.microsoft.com/kb/927847 but I will look at the firewall rules

  lineman60 : Sniffing the traffic during login then blocking the IP it connects to seems to work.
  From Matt