Config changes invalidating cache
As a side-note, check out the Quafzi performance-tweaks module and slides - it caches static blocks and has heaps of other performance improvements.
Since AEM 6.0, AEM provides an OOTB in-memory HTTP cache for anonymous requests with a 60sec TTL.
Please evaluate if this simple cache is sufficient before using this HTTP cache.
In addition to being twice as fast as the default caching implementation it also supports better cache invalidation, which means that your website will appear more up-to-date. The default cache implementation can respond in 0.02s compared to varnishes 0.01s - the difference here is imperceptible - but varnish will scale better and supports better invalidation.
For a caching server to serve pages to your users, it will need to “pretend” to be the web server.
Http Cache provides an effective way to improve performance of an application by caching the full output of a http request and then bypassing the request processing entirely on each subsequent requests.