Change of IP address after actions on Amazon EC2
- Only EC2-VPC instances with Elastic IP addresses retain their public IP address when they are stopped. If your instance is running in EC2-Classic, the EIP address is disassociated when the instance is stopped, and you must re-associate the EIP after restarting the instance. If your instance is not using an EIP, then you need to retrieve your new public DNS name for your instance from the Instances page of the Amazon EC2 console to connect to it.
- Reboot - When you perform a reboot, the same virtual machine instance is rebooted. The original virtual machine instance that was provisioned to you is never returned back to Amazon. The public IP address will not change.
- Assign, reassign, remove an Elastic IP address - An instance can only have one public IP address at any given time. When an instance is assigned an Elastic IP, the EIP becomes its new public IP address and its previous public IP address (if one has already been assigned to it) will be released. For example, if you launch an instance and later assign an Elastic IP to it, the original public IP address of the instance will be replaced by the Elastic IP address. Later, if you disassociate the Elastic IP from the instance, a new public IP address will be assigned to the instance. The original public IP address will not be reassigned to the instance again.
- Relaunch - When you relaunch a server, the running instance is terminated and a new instance is launched in its place. The new instance will have new and different public and private IP addresses than its predecessor because it's a different virtual machine that's been allocated to you.
- Stop and Restart - When you stop a server, the associated instance is actually terminated. Therefore, when you restart the server, another virtual machine instance will be provisioned to you, so it will have new and different public and private IP addresses.