Hello, I use isaserver from few years and I've never understood the strange behavior with the dns, i try to explain: isa have 2 NIC one internal and one external:
ISA NIC INTERNAL IP:192.168.0.5 MASk:255.255.255.0 GW:empty DNS1:192.168.0.6 DNS2:192.168.0.7
ISA NIC EXTERNAL IP:public ip MASK:255.255.255.248 GW: my gw DNS: empty
DC1 NIC IP:192.168.0.6 MASK:255.255.255.0 GW:192.168.0.8 DNS1:DC1 DNS2:DC2
DC2 NIC IP:192.168.0.7 MASK:255.255.255.0 GW:192.168.0.9 DNS1:DC2 DNS2:DC1
When i set in the dc such gateway the IP of the ISASERVER, the latter is not pingable from another machine and i can't navigate on internet, instead when i insert in the dc 2 different gateway ISASERVER work well. Another situation is when a dc go down, isaserver have some problems to switch to the secondary dns, why i have this problems? Is normal? All is inside of the domain, but the domain work well.