HOW TO: Set HTTP Headers for Content Expiration in Internet Information Services (IIS) 5.0

This step-by-step article describes how to set the expiration of Web site content in Internet Information Services (IIS) 5.0.

If your Web site contains time-sensitive information, such as special offers or event announcements, you can configure settings to ensure that information that is no longer valid is not published. When you establish content expiration, you can configure site content to automatically expire any time.

When you enable the content expiration feature, IIS includes the expiration information in the Hypertext Transport Protocol (HTTP) header of the Web page that is sent to the Web browser. The browser then compares the current date with the expiration date to determine whether to display a locally cached page, or request an updated page from the server.

You can set content expiration for Web sites, for virtual folders, or for individual files. Site-level settings apply to all content in that site, folder-level settings apply to all folders and files in that folder, and file-level settings apply to an individual file.

How to Set HTTP Headers for Content Expiration

To set content expiration for a Web site, for a virtual folder, or for a file:

1. Start Internet Services Manager, or open the MMC that contains the IIS snap-in.
2. In the Internet Information Services dialog box, click to expand * server_name, where server_name is the name of the server.
3. Right-click the Web site, folder, or file for which you want to set content expiration (for example, click Default Web Site), and then click Properties.
4. Click the HTTP Headers tab.
5. Click to select the Enable Content Expiration check box.
6. In the Content should box, perform one of the following steps:
   • Click Expire Immediately.
     
     Use this option if you want Web content to expire immediately. The browser does not display the page from the local cache. It requests and displays the latest version of the page from the server.
     
     -or-
   • Click Expire after, and then specify a period of time (in minutes, hours, or days) after the content that expires in the appropriate boxes.
     
     Use this option if you want Web content to expire after a specific length of time.
     
     -or-
   • Click Expire on, and then click an expiration date and time in the appropriate boxes.
     
     Use this option when you want Web content to expire after a specific date and time.
7. Click OK, and then quit Internet Services Manager, or close the IIS snap-in.

Notes

• When you attempt to change the settings for a Web site or for a virtual folder, IIS checks the existing settings on the child nodes (virtual folders and files) that are contained in that Web site or in the virtual folder. If the settings at the lower levels are different, IIS displays an Inheritance Overrides dialog box. To specify which child nodes should inherit the settings that you set at the higher level, click the node or click the nodes in the Child Nodes list, and then click OK. The child node or child nodes inherit the new content expiration settings.
• Typically, content expiration is enabled for Web sites, for folders, or for individual files. However, you can also set content expiration for all Web sites on a server. To do this, right-click * server_name, and then click the Internet Information Services tab. Click WWW Service in the Master Properties box, and then click Edit. Click the HTTP Headers tab, and then configure the content expiration settings that you want.

For more information about content expiration in IIS, see the "Enabling Content Expiration" topic in the "Web Site Management" section of the IIS 5.0 Online Documentation: Note that this link works correctly only if you have IIS installed on your computer.