AWS Interview DropAdvanced TierScenario+50 XP on read
How do you prepare an EC2-based application to fail over to a second AWS region if the primary region has an outage?
Core Summary
Disaster recovery for EC2 is really three separate problems: getting a bootable image into the DR region ahead of time, having a way to launch capacity there fast, and having something outside both regions to redirect traffic. The RTO and RPO you're targeting decide how much of that you keep running warm versus building on demand.
Hints
Hint 1: Name an RTO and RPO before designing anything
Hint 2: AMIs need to already exist in the DR region before the outage, not during it
Hint 3: DNS failover only works if health checks aren't inside the region that's down