Modifying default cache rules
[This topic is pre-release documentation and is subject to change in future releases. Blank topics are included as placeholders.]
Forefront TMG creates default cache rules, as follows:
Microsoft Update Cache rule. This rule is enabled by default after you define a cache drive. It enables caching of Microsoft updates with BITS.
Microsoft Web Access Scenario Cache rule. This rule is created when you run the Web Access Wizard and select to enable caching.
Default rule. Configured by default following installation, this rule specifies that only valid requested objects are retrieved from the cache. If an object is not valid, it is retrieved directly from the Internet. You cannot modify the default cache rule
Modifying a rule
To modify a default rule, do the following:
In the Management console tree, click Firewall Policy.
On the details pane, click the Web Access Policy tab.
On the Tasks tab, click Configure Web Caching.
Click the Cache Rules tab.
On the Cache Rules tab, select the relevant rule, and then click the Edit button.
On the General tab, clear Enable to disable the rule.
On the To tab, add new network objects as destinations for the rule, or modify existing network objects.
On the Cache Store and Retrieval tab, specify how content is retrieved from the cache:
Select Only if a valid version of the object exists in the cache. If no valid version exists, route the request to the server to specify that requests should only be served if a valid version of the requested object is available in the cache. If a valid version does not exist, the request should be served from the requested Web site.
Select If any version of the object exists in the cache. If none exists, route the request to the server to specify that requests should be served with any version of the requested object that is available in the cache. Expired objects will always be served if this setting is configured. If no object can be served from the cache, the request should be served from the requested Web site.
Select If any version of the object exists in the cache. If none exists, drop the request (never route the request to the server) to specify that requests should be served with any version of the requested object that is available in the cache. Expired objects will always be served if this setting is configured. If no object can be served from the cache, the request should be dropped and an error page returned.
In addition, specify how content is stored in the cache:
Select Never, no content will ever be cached to indicate that content requested by this rule is not cached.
Select if source and request headers indicate to cache, and then:
Select Dynamic content to specify that retrieved objects are cached even if they are marked as not cacheable.
Select Content for offline browsing to indicate that content with 302 and 307 codes should be cached.
Select Content required user authentication for retrieval to indicate that content that may require authentication for access should be cached. With this setting enabled, non-authenticated users may be able to access content after it has been cached.
On the HTTP tab, specify how content is retrieved from the cache:
Select Enable HTTP caching to indicate that the rule should cache requested HTTP objects.
In Set TTL of objects (% of the content age), specify how long HTTP objects will remain in the cache based on a percentage of the time the object has existed in the cache. The higher the percentage, the less frequently the cache is updated.
In No less than, indicate the minimum amount of time that the HTTP object remains in the cache.
In No more than, indicate the maximum amount of time that the HTTP object remains in the cache.
Select Also apply these TTL boundaries to sources that specify expiration to specify that even if the source contains expiration data, its TTL will be overridden if it is not within the specified TTL boundaries.
On the FTP tab, specify the amount of time that passes before an FTP object is considered expired.
On the Advanced tab, specify the maximum size of objects that can be cached for the rule and whether SSL responses for SSL-bridged traffic are cached. SSL-tunneled traffic cannot be cached.
Note
On the Advanced tab of the Microsoft Update Cache Rule, the Enable caching of content received through the Background Intelligent Transfer Service (BITS) setting indicates that BITS is enabled for this rule. This setting cannot be modified and is not enabled for any other default rule.
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