EIP versus public IP
A few points about the two types, in case you have not used these much.
Public IPs:
- You choose whether an instance should have a public IP at the time you are launching it
- The address will persist across reboots but not a stop/start
- These come at no extra cost
Elastic IPs:
- You can associate/disassociate an EIP with an instance at any time after it has been launched
- An EIP remains associated across reboots or start/stop operations
- EIPs incur cost (when kept unused)
- EIPs can be migrated between EC2 instances
In light of the IPv4 deficit we are facing today, AWS is cleverly trying to incentivize sensible provisioning by charging for any dormant EIP resources.
Tip
Be a gentleman/lady and release your IPs when you are done with them.
