Just now I webpagetested my blog to see its load time. The major problem it is showing is that keepalive is not set. I want to know how to set this feature. I am using a shared hosting, is this available only on dedicated and if it is possible how much time should I set it?
You should vote with your wallet and change hosting providers. There is no excuse for a shared hosting provider to not enable persistent connections on their shared hosting plans and rewarding them by giving them more money for a dedicated plan is just rewarding them for it.
If you can move the DNS or if your hosting provider directly supports it you can also use a service like cloudflare in front of your hosting provider and they will take care of maintaining persistent connections to the end users. It’s a little difficult to do with some shared hosting providers because you need to move your DNS over but if it’s possible in your config then that could be a way to fix it without having to move your site (the free level of their service will do what you need).