If you have instances in a VPC, they will keep their IP addresses until you destroy them. Turn them off for a week, then back on, and they bounce back with the

If you have instances in a VPC, they will keep their IP addresses until you destroy them. Turn them off for a week, then back on, and they bounce back with the same IP as before. EC2 classic servers will also keep their IP addresses (and hence aws-assigned hostnames) through a reboot (in which the VM itself doesn't actually get torn down), but not through a stop/start cycle. Edit: If your tool works for you, go for it. I don't mean to sound discouraging.