Overview

Using cache to access web pages that are opened repeatedly reduces Internet traffic. Downloaded files are saved to the hard drive of the Kerio Control host so that it is not necessary to download them from the webserver again later.

The cache can be used either for direct access or for access via the proxy server. It can also be used for Kerio Control reverse proxy.  If direct access is being used, the HTTP protocol inspector must be applied to the traffic. In the default configuration of Kerio Control, this condition is met for the HTTP protocol at the default port 80.

Solution

1. In the administration interface, go to Proxy Server > HTTP Cache.
2. Check the option Enable cache for direct access to web.
   
   
3. If you are using a proxy server, check Enable cache on Kerio Control non-transparent proxy server.
4. If you are using a reverse proxy, check Enable cache for Kerio Control reverse proxy.
5. Click Apply.

Configuring TTL

TTL means that you can configure a default time of how long the object is kept in the cache.

1. On tab HTTP Cache, specify the HTTP protocol TTL (default value: 1 day). This setting applies to all objects where no extra cache period is specified.
2. Click URL Specific Settings for objects on specific servers or pages.
3. In the URL Specific Settings dialog, click Add.
4. In the Add URL dialog, specify the URL (or its part) of objects on which the rule will apply. The cache time is specified in hours. Value 0 means that the object will not be kept in the cache.
   
   

Cache status and administration

Kerio Control allows monitoring of the HTTP cache usage as well as the removal of its contents.

At the bottom of the HTTP Cache tab, basic status information is provided such as the current cache size occupied and efficiency of the cache. The efficiency status stands for the number of objects kept in the cache in proportion to the total number of queries (since the startup of Kerio Control). The efficiency of the cache depends especially on user behavior and habits (e.g. If users visit certain web pages regularly if any websites are accessed by multiple users, etc.) and, in a manner, it can be also affected by the configuration parameters. If the efficiency of the cache is permanently low (less than 5 percent), change the cache configuration.

Note: The Clear cache option deletes all objects saved in the cache.