Manual talk:$wgCacheEpoch

How does this work? If the default value is in the past, does that mean that the wiki sees the cache as being "old", and therefore expires the page?

No. Only pages that are cached before the date value are expired. If the value is in the past, the cache created after the date will be kept untouched. --Superxain (talk) 05:09, 18 August 2012 (UTC)