A web application runs on a single On-Demand EC2 instance with no load balancer. As part of routine maintenance, an engineer stops the instance and then starts it again (this is not a reboot). No Elastic IP is associated with the instance. What happens to its public IPv4 address?
- The public IPv4 address is retained exactly as it was before the stop
- The instance is assigned a new public IPv4 address
- The instance permanently loses all public IPv4 connectivity
- AWS automatically converts the address into a permanent Elastic IP
Correct answer: B. The instance is assigned a new public IPv4 address
A standard auto-assigned public IPv4 address is not static: it is released when the instance stops and a new one is assigned when it starts again, which is why the second option is correct. The address is only retained across a stop/start cycle if an Elastic IP address is explicitly allocated and associated with the instance, so the first option only describes the Elastic IP case, which the question rules out. The instance does not lose public connectivity permanently; it simply receives a different public address once it is running again, so the third option confuses temporary reassignment with permanent loss. AWS never automatically converts a dynamic public IP into an Elastic IP; Elastic IPs must be deliberately allocated from the EC2 console or API and then associated, so the fourth option describes something AWS does not do on its own.
Source: AWS EC2 documentation: Elastic IP addresses — public IPv4 address behaviour on instance stop/start