Active-Active for Multi-Regional Resiliency

no, they're unrelated except that the resolvers for the CDN might not exactly match the geo for your ultraDNS (or dyn or home-based powerdns, or whatever)

UltraDNS must be the main way they do their own routing, per comments from an ex-AWS engineer:

"Funfact, everyone here knows that Netflix is on AWS. That's a no brainer, it's plastered all over the AWS site and the Netflix blog. However, if you traceroute their IP space and check their AS numbers, you'll see they do all their own routing. Obviously, this is done with Direct Connect."

http://www.reddit.com/r/IAmA/comments/1e5o4p/iaman_exaws_eng...