Forgot to say all ISA servers are Cache and Firewall. also config looks like                     Internet <br>                          | <br>                    ISAServer4 <br>                          | <br>                       DMZ <br>      --------172.16.0.0/16-----<br>     |                    |                    |<br>   ISA1            ISA2          ISA3 <br>     |                    |                    |<br> Corporate      Education       Library <br> 10.x.0.0/16    10.y.0.0/16     10.z.0.0/16 <br> <br>