Using routing rules.
The scope of this document is to outline what you can do with ISA routing rules. I will not be showing you a step by step configuration of each of the functionalities of routing rules in this tutorial.
Routing rules may apply to both inbound and outbound Web requests. Using routing rules can be very valuable in a scenario where you have more than one ISA server connected to the internet and one of the lines to the internet keeps going down, or is inconsistent in service. In some organizations 24 hour internet access is vital. ISA Server can use a backup route when the main route to the internet is down.
The diagram above displays where Cache routing can be configured within the routing rules option.
Please note: the default routing rule can be configured, but you cannot delete it.
The diagram above displays where firewall chaining is configured. (Right click Network configuration)