FW rule not working when using FQDN in host group

Hey,

one of our customers has the following issue:

He created a host group using the FQDN. He then used this host group to create a FW rule to allow certain traffic. But instead, the traffic is blocked when using FQDN unless the customer performs an nslookup on the destination host. When using the IP address everything works fine.

Server 2008 R2 Datacenter SP1, SEP 12.1.6 MP2

Any ideas?

Thanks in advance!