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I Tested AWS Regional NAT Gateway — Here's Why It Changes Everything

#aws #networking #nat

Last week, I got my hands on the new Regional NAT Gateway for Amazon VPC. After spending a few hours testing it in a real environment, I wanted to share what I learned and why this matters for anyone building on AWS.

The Problem We've Been Living With

Let me paint you a picture. You're running a three-tier application spread across three Availability Zones (us-east-1a, us-east-1b, us-east-1c). Your backend servers sit in private subnets because, well, that's the right thing to do. But these servers need to reach the internet — maybe to pull security patches, call external APIs, or push logs to a third-party service.

Three NAT Gateways. Three public subnets. Three separate route tables to maintain. And if you forgot to set up one AZ properly? Your workloads in that zone lose internet access.

I've seen this go wrong more times than I'd like to admit. Someone provisions a new private subnet, forgets to update the route table, and suddenly their application can't reach external services. Hours of debugging later, they find a missing route.

What Regional NAT Gateway Actually Does

The new Regional NAT Gateway flips this model. Instead of deploying NAT Gateways per Availability Zone, you deploy one at the VPC level. AWS handles the rest.


One NAT Gateway. One route table entry. Done.

Real-World Test: What I Actually Did

I set up a test VPC with private subnets in three AZs. Each subnet had a few EC2 instances running a simple Python script that pings an external API every 30 seconds.

Traditional Setup (Before)

  • 3 NAT Gateways provisioned
  • 3 public subnets created to host these NAT Gateways
  • 3 route tables with individual NAT Gateway targets
  • Total monthly cost estimate: ~$97 (NAT Gateway hourly charges alone)

Regional NAT Gateway (After)

  • 1 Regional NAT Gateway
  • 0 public subnets needed for NAT
  • 1 route table entry pointing to the Regional NAT Gateway
  • Total monthly cost estimate: ~$32

The instances in all three AZs continued reaching the external API without interruption. I deliberately terminated and relaunched instances in different AZs to confirm the routing worked seamlessly. It did.

The Security Angle Nobody's Talking About

Here's something that doesn't get enough attention: public subnets are attack surface.

Every public subnet you create is a potential misconfiguration waiting to happen. Someone attaches an Elastic IP to the wrong instance. A security group gets too permissive. An Internet Gateway route gets added where it shouldn't.

With Regional NAT Gateway, you can architect VPCs where private subnets don't require companion public subnets. Your workloads stay private. The NAT Gateway handles outbound traffic without exposing your infrastructure.

For regulated industries — banking, healthcare, government — this simplified model makes compliance audits less painful. Fewer components means fewer things to document, monitor, and justify.

When Should You Use This?

  • Regional NAT Gateway makes sense when:
  • Your workloads span multiple Availability Zones
  • You want to reduce operational overhead
  • You're building new VPCs and want a cleaner architecture from day one
  • Cost optimization matters (and when doesn't it?)

Stick with zonal NAT Gateways if:

  • You need granular control over which AZ handles outbound traffic
  • Your compliance requirements mandate AZ-level isolation for network components
  • You have existing automation that depends on per-AZ NAT Gateway ARNs

How to Set It Up

The setup is straightforward. When creating a NAT Gateway in the console, you'll now see an option for "Availability zone mode" — select "Regional" instead of the default zonal option.

For Terraform users, the configuration looks like this:

resource "aws_nat_gateway" "regional" {
  connectivity_type = "public"
  subnet_id         = aws_subnet.public.id
  allocation_id     = aws_eip.nat.id

  # This is the key setting
  secondary_allocation_ids = []

  tags = {
    Name = "regional-nat-gateway"
  }
}
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Then update your private subnet route tables:

resource "aws_route" "private_nat" {
  route_table_id         = aws_route_table.private.id
  destination_cidr_block = "0.0.0.0/0"
  nat_gateway_id         = aws_nat_gateway.regional.id
}
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That single route table entry now covers all your private subnets across every AZ.

My Takeaway

After testing this feature, I'm convinced it belongs in most new VPC designs. The reduction in complexity is real. The cost savings are measurable. And the security posture improvement — while harder to quantify — matters.

AWS doesn't always get credit for these incremental improvements. They're not flashy like a new AI service or a major database feature. But for those of us who spend our days building and maintaining cloud infrastructure, this is the stuff that makes our lives easier.

If you're spinning up a new environment or revisiting your network architecture, give Regional NAT Gateway a look. It's one of those changes that seems small until you realize how much cleaner your diagrams become.

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