Keep alive is an concept to allow the same tcp connection for HTTP conversation instead of opening a new one with each new request.
More simply , Keep alive is also known as a persistent connection.
How to enable keep alive
Keep-alive can be enabled using the “Connection: Keep-Alive” in HTTP header.
Enabling keep-alive depends on what server you are using and what you have access to. We cover the most common methods here.
Enable keep-alive using .htaccess
If you do not have access to your webserver config file then you can enable keep-alive using an .htaccess file.
<ifModule mod_headers.c> Header set Connection keep-alive </ifModule>
Adding above code in to your .htaccess file will add keep alive headers to your requests, and will override most webserver or host limitations.
Enable keep-alive in Apache
By default Keep-Alive is disabled in Apache server, We need to edit Apache configuration file and enable Keep-Alive in Apache on CentOS/RedHat Systems. so follow below step to enable it.
Now change the values as shown below:
# # KeepAlive: Whether or not to allow persistent connections # KeepAlive On # # MaxKeepAliveRequests: The maximum number of requests to allow # during a persistent connection. MaxKeepAliveRequests 100 # # KeepAliveTimeout: Number of seconds to wait for the next request from the # same client on the same connection. # KeepAliveTimeout 15
Now restart Apache service using following command:
service httpd restart
Keep-Alive is successfully enabled in your Apache server.