In the console tree of ISA Server Management, click
Cache.
In the details pane, click the Cache Rules or Content
Download Jobs tab.
On the Tasks tab, click Configure Cache
Settings.
On the Advanced tab, select the Cache objects even if
they do not have an HTTP status code of 200 check box.
Notes
To open ISA Server Management, click Start, point to
All Programs, point to Microsoft ISA Server, and then
click ISA Server Management.
For ISA Server 2006 Enterprise Edition, expand
Microsoft Internet Security and Acceleration
Server 2006, expand Arrays, expand
Array_Name, expand Configuration, and then
click Cache.
For ISA Server 2006 Standard Edition, expand Microsoft
Internet Security and Acceleration Server 2006, expand
Server_Name, expand Configuration, and then
click Cache.