After an AZ failure, failover targets for a city’s multi-AZ app are…

Question

After an AZ failure, failover targets for a city’s multi-AZ app are unreachable even though instances launched. What networking baseline should architects verify?

Accepted Answer

That route tables and subnet placement keep failover targets reachable—correct routes to NAT, IGW, or peering as designed after AZ loss — Failover compute doesn’t help if the road signs are wrong—check route tables and subnet placement so the spare AZ can still reach what it needs.

Answer

That only one private subnet exists for all AZs and shares a single broken route entry

Answer

That security groups alone define VPC routing and route tables can be empty

Answer

That every instance uses a public IP in a private subnet with no route to any gateway

After an AZ failure, failover targets for a city’s multi-AZ app are unreachable even though instances launched. What networking baseline should architects verify?

Short Explanation

Full Explanation