ELB is simply a Reverse Proxy with an upstream pointing to your app servers. Last time I checked, I think they were running nginx. I doubt they have advanced

ELB is simply a Reverse Proxy with an upstream pointing to your app servers. Last time I checked, I think they were running nginx. I doubt they have advanced DDOS detection code running on that reverse proxy. Netflix likely implements their own DDOS protection layer somewhere in their routing library. For example, since most resource-intensive Netflix endpoints are protected (you have to login to watch a movie), they could use rate-limiting based on User Account ID.