[bwann]

Using a hostname will be an improvement, but not perfect. It's going to depend on the firewall implementation whether it resolves the hostname to IP address one time and remembers it forever, or periodically refreshes the mapping. I've been particularly burned recently where the firewalls were on the other side of the country and geolocation came into play. The client machines resolved a hostname to A.A.A.A, but the firewalls resolved it to B.B.B.B, thus it looked right at first glance but still blocked the traffic.