In the Forefront TMG Management console, in the tree, click the Web Access Policy node.

On the Tasks tab, click Configure Web Caching.

On the Cache Rules tab, click New. Follow the instructions in the wizard, and note the following:

1. On the Cache Content page, by selecting to cache Dynamic content, if the source and request headers indicate caching, Forefront TMG will cache retrieved objects even if they are marked as not cacheable.
   
   
2. On the Cache Content page, by selecting to cache Content requiring user authentication for retrieval, if the source and request headers indicate caching, Forefront TMG will cache content requested by authenticated users. Content is then served from the cache without verifying access permissions, and non-authenticated users may be able to access it.
   
   
3. On the Cache Advanced Configuration page, the setting Cache SSL Responses applies to SSL bridged traffic. SSL tunneled traffic is not cached. This means that you can cache SSL traffic in reverse caching scenarios, in which internal Web sites are published over SSL, and the SSL request is terminated on the Forefront TMG firewall. Outgoing SSL requests to the Internet cannot be cached.
   
   
4. On the HTTP Caching page, the setting Set TTL of objects (% of the content age) instructs Forefront TMG to keep HTTP objects valid in the cache according to TTL settings. TTL settings are based on the TTL defined in the response header, and the TTL boundaries defined in the cache rule. The percent of the content age is a percentage of the time of the content's existence. The higher the percentage, the less frequently the cache is updated.