IMPORTANT: Read this before implementing one of the configuration files below (for either Varnish 3.x or 4.x+).
USE: Replace the contents of the main Varnish configuration file located in /etc/varnish/default.vcl (root server access required - obviously) with the contents of the configuration you'll use (depending on your Varnish version) from the 2 examples provided below.
IMPORTANT: The following setup assumes a 3 minute (180 sec) cache time. You can safely increase this to 5 mins for less busier sites or drop it to 1 min or even 30s for high traffic sites.
This configuration requires an HTTP Header and a user cookie to identify if a user is logged in a site, in order to bypass caching overall (see how it's done in the Joomla section). If your CMS provides a way to add these 2 requirements, then you can use this configuration to speed up your site or entire server. You can even exclude the domains you don't want to cach