How would you recommend performing that failover, when Elastic Load Balancers only cover a single region? If you host your own load balancer it'll have to be hosted somewhere, and DNS failover seems unpopular [1].
DNS failover is fine, even if its manually triggered. We are almost two and a half hours into this network event, so even if you set a 5 minute TTL on your records and it takes you 15 minutes to respond, you are still way ahead of the game.
The idea that some DNS resolver somewhere caches records longer than TTL is mostly a myth. This is the case rarely on some mobile networks and networks behind satellite uplinks, but they generally have larger network issues anyway.
The idea that some DNS resolver somewhere caches records longer than TTL is mostly a myth. This is the case rarely on some mobile networks and networks behind satellite uplinks, but they generally have larger network issues anyway.