Enabling Keep Alive
When a web browser requests a file from a server, files start downloading one by one i.e. after every single file download connection closes and again it reopens for the new file. So this increases the process, network as well as memory which finally lead to slow loading of website. So if we enable HTTP keep-alive this ensures that on request all the files get loaded via same open connection, this leads to much faster loading of the content.
How to check Keep Alive status
If keep alive is not on then in GTmetrix there will be a notification of keep alive
We can use varvy tool to find out that is keep alive in on mode or in an off mode.