Apache HTTP Server Version 2.2

This document refers to the 2.2 version of Apache httpd, which is no longer maintained. The active release is documented here. If you have not already upgraded, please follow this link for more information.
You may follow this link to go to the current version of this document.
In order to assist folks upgrading, we maintain a document
  describing information critical to existing Apache users. These
  are intended to be brief notes, and you should be able to find
  more information in either the New Features document, or in
  the src/CHANGES file.
This document describes only the changes from 2.0 to 2.2. If you are upgrading from version 1.3, you should also consult the 1.3 to 2.0 upgrading document.
The compilation process is very similar to the one used in
    version 2.0.  Your old configure command line (as
    found in build/config.nice in the installed server
    directory) can be used in some cases.  The most significant change
    required will be to account for changes in module names, in
    particular for the authentication and authorization modules.
    Some details of changes:
mod_imagemapmod_auth_basic,
          mod_authn_file, mod_authz_user, and
          mod_authz_groupfilemod_authz_hostmod_authnz_ldapYour existing version 2.0 config files and startup scripts can
      usually be used unchanged in version 2.2.  Some small
      adjustments may be necessary for particular configurations as
      discussed below.  In addition, if you dynamically load the
      standard modules using the LoadModule directive, then you will
      need to account for the module name changes mentioned above.
If you choose to use the new default
      configuration file for version 2.2, you will find that it has
      been greatly simplified by removing all but the most essential
      configuration settings.  A set of example configuration settings
      for more advanced features is present in the
      conf/extra/ directory of the installed server.  Default
      configuration files are installed in the conf/original
      directory.
Some runtime configuration changes that you may notice:
apachectl option
      startssl is no longer available.  To enable SSL
      support, you should edit httpd.conf to include the
      relevant mod_ssl directives and then use
      apachectl start to start the server.  An example
      configuration to activate mod_ssl has been
      included in conf/extra/httpd-ssl.conf.UseCanonicalName is now
      Off.  If you did not have this directive in your
      config file, you can add UseCanonicalName On to
      retain the old behavior.mod_userdir will no longer act
      on requests unless a UserDir directive specifying a
      directory name is present in the config file.  To restore the
      old default behavior, place the directive UserDir
      public_html in your config file.AuthDigestFile
      from mod_auth_digest has been merged with
      AuthUserFile
      and is now part of mod_authn_file.RewriteRule directives
      are evaluated before ProxyPass ones.mod_cache, which was
      experimental in Apache 2.0, is now a standard module.mod_disk_cache, which was
      experimental in Apache 2.0, is now a standard module.mod_mem_cache, which was
      experimental in Apache 2.0, is now a standard module.mod_charset_lite, which was
      experimental in Apache 2.0, is now a standard module.mod_dumpio, which was
      experimental in Apache 2.0, is now a standard module.Many third-party modules designed for version 2.0 will work unchanged with the Apache HTTP Server version 2.2. But all modules must be recompiled before being loaded.