Set static IP
Set static ip for your oracle ec2 instance
Official aws documentation
Allocation
Log in to your aws account and look for the ec2 service

From the ec2 menu go to Network & Security and click on Elastic IPs

From the elastic ips menu click on Allocate Elastic IP Address

Lastly, just click on Allocate

Association
Now select your ip and click on the actions buttons, then click on Associate Elastic IP address

Finally, select your ec2 instance id and its private ip address. Then click on Associate.

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