فکر کنم با آموزش لینک زیر متوجه موضوع بشوید.
Configuring Automatic Discovery for ISA Server Clients.


Configuring the DNS WPAD Entry In order to use automatic discovery, you must create DNS and DHCP entries so that point to the ISA Server. To configure the DNS WPAD entry, just follow these steps:
1. Click Start | Programs | Administrative Tools | DNS.
2. Expand the console tree and right-click the appropriate forward lookup zone, then click New Alias, which will create a new CNAME record.
3. In the New Resource Record window, enter WPAD for the alias, then enter the fully qualified DNS name for the ISA Server or array, shown in Figure 1. You can also use the Browse button to locate the desired server or array.
4. Click OK to save the record.

Configuring the DHCP WPAD Entry
1. Click Start | Programs | Administrative Tools | DHCP.
2. In the DHCP console, select the desired DHCP server, then click Action | Set Predefined Options.
3. In the Predefined Options and Values window, click the Add button.
4. In the Option Type window, enter WPAD for the name, 252 for the code, and select "string" for the data type, as shown in Figure 2, then click the OK button.

5. In the Predefined Options and Values window, shown in Figure 3, the 252 WPAD entry appears. Now you need to enter a string value for the entry. If you configured DNS to resolve the WPAD entry to the ISA server or array name, type http://WPAD/wpad.dat in the string dialog box. If you did not configure DNS, then you can simply enter the ISA Server or array name as http://server_name/wpad.dat. Make your entry and click the OK button.
6. In the console, expand the server where you created the WPAD entry, select Server Options, then click Action | Configure Options.
7. In the Available Options window, locate and select the check box next to 252 WPAD. In the String Value dialog box, ensure that the correct string appears as entered in Step 5. Click OK.

ISA Server Auto Discovery Publication Automatic Discovery is performed using a Web Proxy Autodiscovery entry in either DNS or DHCP (or both). However, you can also use the ISA Server to answer, or publish auto discovery information about itself on port 80 by default. To use the auto discovery publication feature, just follow these steps:
1. Click Start | Programs | Microsoft ISA Server | ISA Management.
2. In the ISA Management, expand Arrays and select the desired array, or simply select the desired standalone server. Click Action | Properties.
3. Click the Auto Discovery tab. To enable automatic publication, click the "publish automatic discovery information" check box, then click OK.
4. A message appears telling you that the Web proxy service must be restarted for the change to take effect. You have the option of stopping and restarting the service now or later.

Setting the Client Configuration Once you have created your WPAD entries and configured ISA Server to publish auto discovery information, you can enable auto discover for both Firewall and Web Proxy clients. To enable Auto Discovery, follow these steps:
1. Click Start | Programs | Microsoft ISA Server | ISA Management.
2. In the ISA Server Management console, expand Servers and Arrays, then expand the desired array and select Client Configuration.
3. In the details pane, double-click Web Browser and click the Automatically Discover Settings check box on the General tab. Click OK.
4. In the details pane, double-click Firewall Client. On the General tab, click the Enable ISA Firewall automatic discovery in Firewall Client check box. Click OK.