The client uses the HTTP Keep-Alive header to indicate to the Web server that it requires a persistent connection. After the Web server receives this header, it waits for a subsequent request from the same client. The time that the Web server waits before closing the connection is specified in the KeepAliveTimeout directive.
The default time specified for this directive in the httpd.conf file is 15 seconds. After a lapse of 15 seconds, the Apache Web server processes the request already received from the client and then closes the connection.
The default time specified in the httpd.conf file is considered to be the perfect value for this directive, so leave this directive unaltered.