Servers are behind security proxy?
Security proxy services act as a front end for web traffic. They mitigate attacks and accelerate site traffic.
Using a security proxy service hides the IP of your servers from the attacker, thus making denial-of-service attacks more difficult to perform. Security proxies are provided by specialized companies that maintain geographically distributed servers and a lot of bandwidth to withstand attacks. The security proxies may utilize an IP reputation system and force botnet IP addresses to go through additional CAPTCHAs before being allowed to connect.
Security proxies also mitigate legal threats against your hosting provider. Without public knowledge of who is hosting the servers, it is more difficult to take legal action against the service.