Offline Cache in Firefox

Firefox web browser maintains three different kinds of Cache,  Memory Cache, Disk Cache and Offline Cache. While all three type of Caching are equally important at different scenario, We are going to focus on Offline Caching in Firefox.

Firefox Cache can be viewed using Cache viewer by typeing "about:cache" in the URL box and hitting enter. The offlline Cache is stored at 

Application Data\Mozilla\Firefox\Profiles\0x6pj2d8.default\OfflineCache

The offline caching mechanism has been introduced in Firefox 3 only and is not availble in the previous versions of firefox.

Firefox: DNS Caching

To enhance the user experience and serve the web-pages faster, Firefox has in-built DNS caching mechanism. Firefox browser being compatible with multiple platforms, it does make perfect sense to not depend on the operating system for DNS caching. This caching is turned on by default and stores the IP Address of all the recently visited websites allowing Firefox to avoid a request to DNS for getting the IP Address and thus serving the page faster.

The DNS Caching in Firefox has been designed keeping the normal browsing behaviour of users and could be be a problem when you want to set the IP Address manaully for some testing purpose (e.g. via a hosts file). However, for the benefit such advanced users who use hosts file to manually control the IP Address, Firefox has given a way to disable the DNS Caching feature. This is done by creating an integer preference value "network.dnsCacheExpiration" in FireFox about:config and setting a value '0' (zero) for this.

If Firefox DNS Caching is disabled, it uses the DNS Caching provided by OS.