How to break the connection when there are a lot of them at the same time (apache)?

Question

DDoS Protection

There is a server (apache2, php5, mysql...) on which the sites lie. When entering any site, if you hold down CTRL + R in the browser, then the page is reloaded, and a large number of such requests are obtained in a row.
The problem is that each request is executed to the end and a queue of requests is formed.
How to avoid it? Probably it is necessary: ​​if the browser terminates the request, then terminate it on the server?