Data Compression Using mod_deflate

The mod_deflate module provides the DEFLATE output filter that allows output from your server to be compressed before being sent to the client over the network. Currently mod_deflate is using with newer version of Apache. mod_deflate is the replacement of mod_gzip which was used with older verion of Apache.

Enabling Compression

By default mod_deflate modules are enabled in Apache. To make sure check following line in Apache configuration file.

LoadModule deflate_module modules/mod_deflate.so

Enable mod_deflate by editing apache conf(vhost.conf) file for particular website,

<Directory "/path/">
       <IfModule mod_mime.c>
                AddType application/x-javascript .js
                AddType text/css .css
        </IfModule>
        <IfModule mod_deflate.c>
                AddOutputFilterByType DEFLATE text/css application/x-javascript text/x-component text/html text/plain text/xml application/javascript
        </IfModule>
        Header append Vary User-Agent env=!dont-vary
    </Directory>

OR

Enable mod_deflate by editing apache conf(httpd.conf) file,

Add the following lines to configure mod_deflate in your apache configuration file.

 <IfModule mod_deflate.c>
  # compress text, html, javascript, css, xml:
  AddOutputFilterByType DEFLATE text/plain
  AddOutputFilterByType DEFLATE text/html
  AddOutputFilterByType DEFLATE text/xml
  AddOutputFilterByType DEFLATE text/css
  AddOutputFilterByType DEFLATE application/xml
  AddOutputFilterByType DEFLATE application/xhtml+xml
  AddOutputFilterByType DEFLATE application/rss+xml
  AddOutputFilterByType DEFLATE application/javascript
  AddOutputFilterByType DEFLATE application/x-javascript
  AddOutputFilterByType DEFLATE image/x-icon
</IfModule>

To set the no-gzip note for a particular browser, so that no compression will be performed.

<Directory /var/www/html/>
    <IfModule mod_mime.c>
        AddType application/x-javascript .js
        AddType text/css .css
    </IfModule>
    <IfModule mod_deflate.c>
        AddOutputFilterByType DEFLATE text/css application/x-javascript text/x-component text/html text/plain text/xml application/javascript
        <IfModule mod_setenvif.c>
            BrowserMatch ^Mozilla/4 gzip-only-text/html
            BrowserMatch ^Mozilla/4\.0[678] no-gzip
            BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
        </IfModule>
    </IfModule>
    Header append Vary User-Agent env=!dont-vary
</Directory>

Restart the apache service to complete the process

# service httpd restart

Testing Compression

After configuring compression in Apache we can see that content is being send by web server is compressed by mod_defalte by using below URL.
http://www.whatsmyip.org/http-compression-test/

Ref : http://tecadmin.net/how-to-enable-gzip-compression-on-apache/