In the procedure in Walkthrough: Configure the network adapter cards on the reverse proxy computer, the ISA Server computer has two network adapters:

• A public or external network adapter, which is exposed to the clients that will attempt to connect to your Web site (usually over the Internet).
  
  
• A private or internal network interface, which is exposed to the internal Web server.
  
  

You must assign one or more IP addresses to the external network adapter and at least one IP address to the internal network adapter.