This is exactly how EdgeCast CDN (now Verizon) has worked for many years, down to the ip per region approach. So this is known for a long time to be a good way

This is exactly how EdgeCast CDN (now Verizon) has worked for many years, down to the ip per region approach. So this is known for a long time to be a good way to do global content delivery. I'm curious why linkedin didn't just use a commercially available CDN service for this? Could save them a lot of time and maintenance, while probably getting a better result because CDNs have this down to the details.