Configuring expiration of cached pages setting in Drupal 7

Working with performance enhancement tools such as external caching can be doen in Drupal 7. When using these types of tools, you may want to set the maximum time the tool can store Drupal 7 pages in the cache. This setting is known as the 'Maximum Cache Lifetime' and is easily adjusted in Drupal 7 by following these steps.

How to enable and set the Expiration of cached pages in Drupal 7:

1. Log into your Drupal 7 admin dashboard.
2. Find the Configuration option on the top menu bar and click on that option.
   
3. You are now on the Configuration screen. Find the Development category and click on the Performance link.
4. This brings you to the Performance screen. Find the Expiration of cached pages dropdown under the Caching section. Select your desired timeframe from the dropdown list.
   
5. Scroll to the bottom of the screen and click on the Save Configuration button.

Now you know how to enable and set the Maximum Cache Lifespan setting for external caches in Drupal 7.