Do I need a NAT gateway in each subnet?

You only need a NAT Gateway if your Lambda function will be accessing the internet. Assuming that you do need a NAT, you can just use one NAT Gateway for all your private subnets. All your public subnets must route to an Internet Gateway for non-local addresses. This is what makes the subnet public.

How do I add a NAT gateway to a private subnet in AWS?

Configure NAT Gateway for private subnets in your VPC:

1. Navigate to the AWS console -> Services.
2. Go to the Networking & Content Delivery section and click VPC.
3. Navigate to Virtual Private Cloud -> NAT Gateways -> Create NAT Gateway.

Can you have multiple NAT gateways?

If you require more bandwidth, you can split your resources into multiple subnets and create a NAT gateway in each subnet.

Can AWS subnets communicate with each other?

All subnets within a VPC can communicate with each other by default. In fact, the only way to prevent this is by defining Network ACLs that Deny traffic. So, yes, an instance in one private subnet can connect to an instance in another private subnet (in the same VPC). Just use the Private IP address to connect.

Can subnet be in multiple availability zones?

Can a subnet span Availability Zones? No. A subnet must reside within a single Availability Zone.

Can two subnets have same CIDR?

You cannot have multiple subnets with the same (or overlapping) CIDR blocks in the same VPC, though, because AWS treats it as one continuous network. Reserved RFC 1918 CIDR blocks (AWS will let you use any of these for your VPC): 10.0. 0.0/8 (The most commonly used, because it’s the largest)

Do I need a NAT gateway for EC2?

You can create a NAT gateway for EC2 instances in a private VPC subnet to connect securely over the Internet. Instead, it is necessary to use network address translation (NAT) to map the private IP addresses to a public address for requests, and then map the public IP address back to private addresses for the response.