21.1.1. Features of Apache HTTP Server 2.2

Apache HTTP Server 2.2 features the following improvements over version 2.0 :

Improved caching modules (mod_cache, mod_disk_cache, mod_mem_cache).
A new structure for authentication and authorization support, replacing the authentication modules provided in previous versions.
Support for proxy load balancing (mod_proxy_balancer)
support for handling large files (namely, greater than 2GB) on 32-bit platforms

The following changes have been made to the default httpd configuration:

The mod_cern_meta and mod_asis modules are no longer loaded by default.
The mod_ext_filter module is now loaded by default.

If upgrading from a previous release of Red Hat Enterprise Linux, the httpd configuration will need to be updated for httpd 2.2. For more information, refer to http://httpd.apache.org/docs/2.2/upgrading.html