RDS instance in private subnet

Question

Given a VPC, can I not explicitly mention which subnets the RDS instance should exist?

I have created a VPC 10.0.0.0/24 with three subnets as shown below:

• REST servers - 10.0.0.0/25

• RDS - AZ1 - 10.0.0.128/26

• RDS - AZ2 - 10.0.0.192/26

When creating the DB, I am able to provide the VPC name. It seems, all subnets of this VPC are automatically selected. I am not able to specify the two subnets (as shown in the list above). There is an option for public accessibility which I have set to No. Therefore, even though all subnets seem to be applied for this RDS instance, it seems that, it will be accessible only from the REST servers subnet.

Answer 1

You need to create a new subnet group and assign it while creating a new RDS. Make note that existing RDS doesn't reflect when you change the subnet group, hence you need to create a new one.