If the environment managed by Active Roles is located behind a firewall, then the following ports must be open between the Active Roles Administration Service and managed environment.
For instance, if there is a firewall between Active Roles and DNS, then port 15172 must be open (Inbound/Outbound) on the Active Roles host (or the firewall between Active Roles and Exchange) and port 53 must be open on the DNS server (or the firewall between Active Roles and DNS).