Although the below works in the majority of cases, it is important to test your site after completing the change to ensure there are no issues and you may need to make some changes to the files you are allowing to be compressed if you do see any issues.
First off, check that mod_deflate is enabled within your Apache configuration. The easiest way to do this is to output the configuration of Apache and check for “deflate_module” using the following command:
# apachectl -M | grep deflate
If this does not show, you will need to pre-append “LoadModule deflate_module modules/mod_deflate.so” to the below content.
The below directives should be added to your Apache configuration. The best way to manage this is to create a new configuration file within the Apache directory (the below locations may need to be adjusted for your environment).
# vi /etc/httpd/conf.d/deflate.conf
Then add the below:
AddType text/css .css
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4.0 no-gzip
BrowserMatch bMSIE !no-gzip !gzip-only-text/html
Header append Vary User-Agent env=!dont-vary
Once this file is saved, check that the Apache configuration is still valid, before restarting Apache.
# apachectl -t
# service httpd restart
Stopping httpd: [ OK ]
Starting httpd: [ OK ]
Now this is complete, you can test your site to check for compression and what should be a drastically improved load time.