Is there a way to detect if a website uses a a known DDoS protection service (Prolexic for example)?

Is there a way to detect if a website uses a a known DDoS protection
service (Prolexic for example)?

Is there a way to check if a website uses a a known DDoS protection
service (Prolexic for example)?
My first guess was to look at the IP address the website resolves (and see
if it matches the protection service provider) to, but I am not sure that
proves anything.