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Enable Automatic Detection and Configuration of Browser Settings

You can configure your network so that Internet Explorer is automatically customized the first time it is started. This can help reduce administrative overhead and help desk calls about browser settings.

Automatic detection of browser settings, which is based on Web Proxy AutoDiscovery (WPAD), is supported by both Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS). With the appropriate settings, DHCP and DNS servers can automatically detect and configure browser settings. This feature builds on existing automatic configuration technologies, in which a browser can be configured from a central location with an automatic configuration URL (.ins file) or a Javascript proxy configuration file (.js, .jvs, or .pac).

With automatic detection, the browser can be automatically configured when it is started, even if it was not first customized by the administrator. For example, if a user were to download a noncustomized browser from the Internet, instead of installing a customized version from the corporate servers, automatic detection can automatically configure and customize the user's browser.

To specify that you want to set up automatic detection of browser settings in Internet Explorer Administration Kit 7 (IEAK 7), when you run the Internet Explorer 7 Customization Wizard, on the Automatic Configuration page, select the Automatically detect configuration settings check box.

Automatic detection of browser settings for DHCP and DNS

A DHCP server enables the administrator to centrally specify global and subnet-specific TCP/IP parameters, and to define parameters for clients by using reserved addresses. When a client computer moves between subnets, it is automatically reconfigured for TCP/IP when the computer is started.


Your DHCP server must support the DHCPINFORM message (this is the same requirement for the DHCP server in Windows 2000 and Windows XP).

DNS is a set of protocols and services on a TCP/IP network that allow users to search for other computers using hierarchical, user-friendly names (hosts) instead of numeric IP addresses.

Using DHCP with automatic detection works best for users connected to a local area network (LAN), while DNS enables the detection of settings for both LAN-based and dial-up users. Although DNS can handle network and dial-up users, DHCP provides faster access for LAN users and allows greater flexibility in specifying configuration files.

To enable automatic detection of browser settings, you need to configure specific settings on DNS servers, DHCP servers, or both.

Enabling automatic detection of browser settings on DHCP

To set up automatic detection of browser settings on a DHCP server, you need to create a new option type with a code number of 252. For the value associated with the code, type the URL that points to your configuration file. This file can be a .pac, .jvs, .js, or .ins configuration file.

For specific information about configuring your DHCP server, consult your server documentation.



Enabling automatic detection on DNS

To enable automatic detection of browser settings on DNS, you need to configure either the host record or the CNAME alias record in the DNS database file.

Host record

A host record is used to statically associate host (computer) names to IP addresses within a zone. A host record contains entries for all hosts that require static mappings, such as workstations, name servers, and mail servers.

The syntax is: <host name> IN A <ip address of host>

For example:

corserv IN A

nameserver2 IN A

mailserver1 IN A

CNAME record

These records are sometimes called aliases, but are technically referred to as canonical name (CNAME) entries. These records enable you to use more than one name to point to a single host. Using canonical names makes it easy to do such things as host both an FTP server and a Web server on the same computer.

Configuring a DNS database file for automatic detection of browser settings

In the DNS database file, enter a host record named wpad that points to the IP address of the Web server that contains the .pac, .jvs, .js, or .ins automatic configuration file. Or, enter a CNAME alias named wpad that points to the name (the resolved name, not the IP address) of the server that contains the .pac, .jvs, .js, or .ins automatic configuration file.

After the record is added and the database file is propagated to the server, the DNS name wpad.domain.com should resolve to the same computer name as your server that contains the automatic configuration file.


When using DNS, Internet Explorer constructs a default URL template based on the host name wpad. For example: http://wpad.domain.com/wpad.dat. Therefore, on the Web server wpad, you must set up a file or redirection point named Wpad.dat, which delivers the contents of your automatic configuration file.

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