Consider the following recommendations for SQL Server database on AWS:
- For increased security, deploy the SQL Server database in a private subnet.
- Allow only application servers or a Jump Box within the VPC to access the database instances.
- When configuring an SQL Server failover virtual IP address, it is recommended to choose an elastic IP.
- An Elastic IP address is a public IPv4 address that you can allocate to your account. You can associate it to and disassociate it from instances as you require. It is allocated to your account until you choose to release it.A public IP address is assigned to your instance from Amazon's pool of public IPv4 addresses and is not associated with your AWS account. When a public IP address is disassociated from your instance, it is released back into the public IPv4 address pool, and you cannot reuse it.
For more information, see Amazon EC2 instance IP addressing - Amazon Elastic Compute Cloud