Avalanche has 3 ways to add DNS support for domain name testing.
(1) DNS Hosts file. This is a build-in file with highest priority, under GUI->Client->Profiles->DNS->"Use DNS Hosts File"
(2) Domain name resolved through management port. GUI->Administration->Appliances->Network Configuration->Network Configuration->Primary/Secondary DNS
(3) Domain name resolved through test port. GUI->Client->Port->Test DNS enable, add Primary/Secondary DNS server in the blank.