AWS Regional NAT Gateway: Complete Guide to Cost Optimization

Introduction

Amazon recently introduced Regional NAT Gateway - a game-changing feature that simplifies VPC networking and can reduce costs significantly. This breakthrough eliminates the need for multiple NAT Gateways per region while maintaining high availability and improving failover performance.

📊 Cost Savings Disclaimer: The cost savings presented in this guide are based on my specific infrastructure setup with 3 Availability Zones. Your actual savings will vary depending on:

• Number of AZs in your deployment
• Data transfer volumes
• Regional pricing differences
• Existing infrastructure configuration

All calculations use US East 1 pricing as of January 2026. Always use the AWS Pricing Calculator for your specific scenario.

In this guide, we'll explore:

• Deep comparison: Traditional vs Regional NAT Gateway
• Real-world cost analysis (based on common scenarios)
• Complex architecture examples with microservices
• Step-by-step AWS Console setup
• Production-ready Terraform implementation

Bottom Line: Potential to save $800+ annually per environment while simplifying operations and improving reliability.

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What is a NAT Gateway?

NAT Gateway enables instances in private subnets to access the internet while blocking inbound connections. It's a managed AWS service that handles:

• Network address translation
• Automatic scaling (up to 45 Gbps)
• 55,000 simultaneous connections
• 99.99% availability SLA

Pricing (US East 1):

• $0.045/hour = $32.85/month
• $0.045 per GB processed
• Cross-AZ data transfer: $0.01/GB

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Traditional NAT Gateway: The Old Way

Architecture

Before Regional NAT Gateway, high availability required one NAT Gateway per Availability Zone.

Figure 1: Traditional NAT Gateway setup requiring 3 separate NAT Gateways ($33 each), 3 Elastic IPs, and 3 route tables. Each AZ is completely isolated. Total Cost: $98.55/month

Setup Requirements:

• 3 NAT Gateways (one per AZ)
• 3 Elastic IPs
• 3 public subnets
• 3 route tables for private subnets
• Each AZ isolated

Traditional NAT: Pros & Cons

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Regional NAT Gateway: The Modern Way

Revolutionary Architecture

Game Changer: One NAT Gateway automatically serves all Availability Zones with built-in redundancy.

Figure 2: Regional NAT Gateway architecture with ONE NAT Gateway serving all AZs through a single shared route table. Total Cost: $32.85/month - Automatic failover across AZs with no cross-AZ data transfer charges

How It Works

Behind the Scenes:

1. AWS deploys multiple NAT nodes across AZs automatically
2. Single NAT Gateway ID with transparent failover
3. Traffic routes to nearest NAT node (<1 second failover)
4. No cross-AZ charges for NAT Gateway traffic
5. Same 45 Gbps performance

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Head-to-Head Comparison

Feature Comparison Matrix

Score: Regional NAT wins 10-2 ✨

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Cost Analysis: Example Scenarios

⚠️ Important: These calculations are based on my production environment with:

• Region: US East 1 (N. Virginia)
• Setup: 3 Availability Zones
• Pricing: As of January 2026
• Use case: Standard web application workload

Your costs may differ based on:

• Geographic region (prices vary by region)
• Number of Availability Zones deployed
• Data transfer patterns and volumes
• Peak bandwidth requirements
• Cross-region data transfer needs

Use these as reference examples only. Always calculate costs for your specific use case using the AWS Pricing Calculator.

Monthly Cost Breakdown

Scenario 1: Startup (500 GB/month)

Scenario 2: Medium Business (2 TB/month)

Scenario 3: Enterprise (10 TB/month)

💡 Key Insight: Savings percentage is higher for smaller workloads due to fixed NAT Gateway hourly costs ($0.045/hour), while data processing costs ($0.045/GB) remain constant.

💭 Remember: These scenarios use US East 1 pricing with 3 AZs. Calculate your specific costs at AWS Pricing Calculator.

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Real-World Architecture Examples

Example 1: High-Traffic Web Application

Figure 3: Production web application with auto-scaling across 3 AZs, Aurora PostgreSQL, ElastiCache Redis, and a single Regional NAT Gateway handling all outbound traffic to external APIs (Stripe, SendGrid, Twilio, etc.)

Architecture Components:

• Frontend: Application Load Balancer distributing traffic
• Compute: Auto-scaling EC2 instances across 3 AZs
• Database: Aurora PostgreSQL (Multi-AZ) for high availability
• Cache: ElastiCache Redis (Cluster Mode) for session management
• NAT: Regional NAT Gateway serving all AZs
• External APIs: Stripe, SendGrid, Twilio, DataDog, Auth0

Cost Comparison:

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Example 2: Real-Time Analytics Platform (Complex Microservices)

This advanced example shows Regional NAT Gateway handling high-throughput data processing with multiple microservices.

Use Case: Real-time e-commerce analytics processing 100K events/second

Figure 4: Enterprise-scale real-time analytics platform with Lambda ingestion, Kafka (MSK), 6 ECS Fargate microservices, and 5 different databases. Regional NAT Gateway handles 10TB/month outbound traffic to external monitoring, API, and data services.

Architecture Details:

Traffic Patterns:

• 📤 Outbound: 10 TB/month
  • Docker image pulls: 2 TB
  • API calls to partners: 3 TB
  • Monitoring/logging: 1 TB
  • Software updates: 500 GB
  • Backup/sync: 3.5 TB

Cost Comparison for This Architecture:

Traditional (3 NAT Gateways):
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  • 3 NAT Gateways:           $98.55/month
  • Data processing (10TB):   $450.00/month
  • Cross-AZ transfer:        $50.00/month
  ────────────────────────────────────────────────
  Total:                      $598.55/month
  Annual:                     $7,182.60/year

Regional NAT:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  • 1 Regional NAT:           $32.85/month
  • Data processing (10TB):   $450.00/month
  • Cross-AZ transfer:        $0.00/month (free!)
  ────────────────────────────────────────────────
  Total:                      $482.85/month
  Annual:                     $5,794.20/year

💰 SAVINGS:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  • Monthly:                  $115.70 (19% reduction)
  • Annual:                   $1,388.40
  • 3-Year:                   $4,165.20

Additional Benefits:

• ✅ Simplified networking (1 route table vs 3)
• ✅ Faster failover (<1 second vs 30-60 seconds)
• ✅ Single egress IP for whitelist management
• ✅ No cross-AZ data transfer fees
• ✅ Automatic high availability
• ✅ Reduced operational complexity

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AWS Console Setup Guide (Step-by-Step Walkthrough)

Prerequisites: You need a VPC with at least one public subnet and three private subnets already created.

⏱️ Total Time: 10-15 minutes

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Step 1: Allocate Elastic IP Address

Why First? You need an Elastic IP before creating the NAT Gateway.

1.1 Navigate to Elastic IPs

AWS Console → Search bar (top) → Type "VPC" → Press Enter
On left sidebar → Click "Elastic IPs" (under "Virtual Private Cloud")

1.2 Allocate New Address

• You'll see a page titled "Elastic IP addresses"
• Click the orange "Allocate Elastic IP address" button (top right)

1.3 Configuration Screen

Figure: Elastic IP allocation form - Select Amazon's pool, add Name tag, and click Allocate

1.4 Success!

• You'll see: "Successfully allocated Elastic IP address"
• Note down the allocated IP (e.g., 54.123.45.67)
• You'll see a new entry with status "Available (not associated)"

⏱️ Time: ~30 seconds

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Step 2: Create Regional NAT Gateway

2.1 Navigate to NAT Gateways

AWS Console → On left sidebar
→ Click "NAT gateways" (under "Virtual Private Cloud")

2.2 Start Creation

• You'll see "NAT gateways" page (probably empty if first time)
• Click orange "Create NAT gateway" button (top right)

2.3 Fill Out the Form

Here's exactly what you'll see:

Figure: NAT Gateway creation form - Fill in name, select PUBLIC subnet, choose Public connectivity, and select your Elastic IP

Key points:

• Name: regional-nat-production
• Subnet: Select a PUBLIC subnet (not private!)
• Connectivity type: Public (selected by default)
• Elastic IP: Choose the EIP you allocated in Step 1
• Tags: Add identifying tags for better organization

2.4 Wait for Creation

• Status changes from "Pending" → "Available" (~2-3 minutes)
• ☕ Grab coffee while waiting
• You'll see: "Successfully created NAT gateway"

2.5 Note Your NAT Gateway ID

• Find your NAT Gateway in the list
• ID looks like: nat-0abc123def456789
• Copy this ID - you'll need it for the route table!

⏱️ Time: ~3 minutes

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Step 3: Create Shared Private Route Table

3.1 Navigate to Route Tables

AWS Console → Left sidebar
→ Click "Route tables" (under "Virtual Private Cloud")

3.2 Start Creation

• You'll see a list of existing route tables
• Click orange "Create route table" button (top right)

3.3 Basic Configuration

Figure: Route table creation form - Name your route table and select the VPC

3.4 Success Message

• "Successfully created route table rtb-xyz789"
• Click "Close" button

⏱️ Time: ~30 seconds

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Step 4: Add Route to NAT Gateway

4.1 Select Your New Route Table

• In the route tables list, check the box next to private-route-table-regional
• Bottom panel opens with tabs: Details, Routes, Subnet associations, etc.

4.2 Add Internet Route

• Click the "Routes" tab (bottom panel)
• You'll see one default route: 10.0.0.0/16 → local
• Click "Edit routes" button (right side)

4.3 Add NAT Gateway Route

Figure: Edit routes screen - Add 0.0.0.0/0 route pointing to your NAT Gateway

Steps to add the route:

1. Click "Add route" button
2. Destination field: Type 0.0.0.0/0
3. Target dropdown: Select "NAT Gateway"
4. Another dropdown appears: Select your NAT Gateway nat-0abc123def456789
5. Click "Save changes"

4.4 Verify Routes Your routes should now show:

Destination      Target                Status
10.0.0.0/16     local                 Active
0.0.0.0/0       nat-0abc123def...     Active  ✓

⏱️ Time: ~1 minute

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Step 5: Associate Private Subnets

This is THE KEY STEP that makes Regional NAT work!

5.1 Still in Route Table View

• Make sure private-route-table-regional is selected
• Click "Subnet associations" tab (bottom panel)

5.2 Associate Subnets

• You'll see two sections:
  • "Explicit subnet associations" (currently 0 subnets)
  • "Subnets without explicit associations"
• Click "Edit subnet associations" button

5.3 Select ALL Private Subnets

Figure: Subnet associations screen - Check ALL 3 private subnets (one per AZ)

🎯 THIS IS THE KEY STEP! - This makes all 3 AZs use the same NAT Gateway!

Important:

• ✅ Check: All 3 private subnets (one per AZ)
• ❌ Uncheck: Any public subnets
• This is what makes it "Regional" - one route table for all AZs!

5.4 Verify Associations You should now see:

Explicit subnet associations (3)
────────────────────────────────
Subnet ID        Subnet name              CIDR         AZ
subnet-111       private-subnet-1a        10.0.1.0/24  us-east-1a  ✓
subnet-222       private-subnet-1b        10.0.2.0/24  us-east-1b  ✓
subnet-333       private-subnet-1c        10.0.3.0/24  us-east-1c  ✓

⏱️ Time: ~1 minute

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Step 6: Verify the Setup

6.1 Check NAT Gateway Status

VPC Dashboard → NAT Gateways
→ Select your NAT Gateway
→ Status should show: "Available"  ✓

6.2 Launch Test Instance (Optional)

To verify your Regional NAT Gateway is working correctly, launch a test EC2 instance.

Instance Configuration:

• AMI: Amazon Linux 2023
• Instance type: t2.micro (free tier)
• VPC: Your VPC
• Subnet: One of the private subnets (e.g., private-subnet-1a)
• Auto-assign public IP: Disabled
• Security group: Allow outbound HTTPS (443) and HTTP (80)

Connect to Instance:

Use EC2 Instance Connect or AWS Systems Manager Session Manager to access the instance (no bastion host or SSH keys needed).

Run Connectivity Tests:

Once connected to your instance, run these commands:

Test 1: Verify NAT Gateway IP

curl ifconfig.me

Expected output: 54.123.45.67 (your Regional NAT Gateway's Elastic IP)

Test 2: Verify Internet Access

curl -I https://www.google.com

Expected output: HTTP/2 200 ✓

Test 3: Verify DNS Resolution

nslookup google.com

Expected: Should resolve successfully with IP addresses ✓

Test 4: Verify File Download

curl -O https://www.google.com/robots.txt
ls -lh robots.txt

Expected: File should download successfully ✓

6.3 Verify All AZs Use Same NAT Gateway

To confirm all Availability Zones route through the same Regional NAT Gateway:

1. Launch instances in different private subnets (private-subnet-1b, private-subnet-1c)
2. Connect to each instance
3. Run: curl ifconfig.me

Expected Result: All instances should return the same IP address - your Regional NAT Gateway's Elastic IP!

This confirms your Regional NAT Gateway is successfully serving all Availability Zones. 🎉

⏱️ Time: ~5 minutes (if testing)

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Step 7: Monitor Your Setup

7.1 View NAT Gateway Metrics

VPC Dashboard → NAT Gateways
→ Select your NAT Gateway
→ Click "Monitoring" tab

You'll see graphs for:

• Active connection count
• Bytes in/out
• Packets in/out
• Error count

7.2 Set Up CloudWatch Alarm (Optional)

Same page → Click "Create alarm"
→ Metric: BytesOutToDestination
→ Threshold: 10 GB (10,000,000,000 bytes)
→ Action: Send SNS notification

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✅ Setup Complete Checklist

Use this to verify your setup:

• [ ] ✅ Elastic IP allocated and showing in VPC dashboard
• [ ] ✅ NAT Gateway status is "Available"
• [ ] ✅ NAT Gateway is in a public subnet
• [ ] ✅ Route table has 0.0.0.0/0 → NAT Gateway route
• [ ] ✅ All 3 private subnets are associated with the route table
• [ ] ✅ Test instance can access internet
• [ ] ✅ curl ifconfig.me shows NAT Gateway's Elastic IP
• [ ] ✅ CloudWatch monitoring is showing data

🎉 You now have a Regional NAT Gateway serving all Availability Zones!

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Common Issues & Solutions

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What You Just Built

Your Setup:
├── 1 Elastic IP (e.g., 54.123.45.67)
├── 1 Regional NAT Gateway (in public subnet, any AZ)
├── 1 Shared Route Table (pointing to NAT Gateway)
└── 3 Private Subnets (all using the same route table)
    ├── private-subnet-1a (us-east-1a)
    ├── private-subnet-1b (us-east-1b)
    └── private-subnet-1c (us-east-1c)

Monthly Cost: $32.85 (vs $98.55 for 3 NAT Gateways!)

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Production Terraform Configuration

terraform {
  required_version = ">= 1.6"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

# VPC
resource "aws_vpc" "main" {
  cidr_block           = "10.0.0.0/16"
  enable_dns_hostnames = true
  enable_dns_support   = true

  tags = { Name = "regional-nat-vpc" }
}

# Internet Gateway
resource "aws_internet_gateway" "main" {
  vpc_id = aws_vpc.main.id
  tags   = { Name = "main-igw" }
}

# Public Subnet
resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.main.id
  cidr_block        = "10.0.0.0/24"
  availability_zone = "us-east-1a"
  tags              = { Name = "public-subnet" }
}

# Private Subnets (3 AZs)
resource "aws_subnet" "private" {
  count             = 3
  vpc_id            = aws_vpc.main.id
  cidr_block        = "10.0.${count.index + 1}.0/24"
  availability_zone = ["us-east-1a", "us-east-1b", "us-east-1c"][count.index]
  tags              = { Name = "private-subnet-${count.index + 1}" }
}

# Elastic IP for Regional NAT
resource "aws_eip" "nat" {
  domain     = "vpc"
  depends_on = [aws_internet_gateway.main]
  tags       = { Name = "regional-nat-eip" }
}

# Regional NAT Gateway
resource "aws_nat_gateway" "regional" {
  allocation_id     = aws_eip.nat.id
  subnet_id         = aws_subnet.public.id
  connectivity_type = "public"

  tags = {
    Name = "regional-nat-gateway"
    Type = "regional"
  }
}

# Public Route Table
resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.main.id
  }

  tags = { Name = "public-route-table" }
}

resource "aws_route_table_association" "public" {
  subnet_id      = aws_subnet.public.id
  route_table_id = aws_route_table.public.id
}

# Single Shared Private Route Table
resource "aws_route_table" "private_regional" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block     = "0.0.0.0/0"
    nat_gateway_id = aws_nat_gateway.regional.id
  }

  tags = { Name = "private-route-table-regional-shared" }
}

# Associate ALL private subnets
resource "aws_route_table_association" "private" {
  count          = 3
  subnet_id      = aws_subnet.private[count.index].id
  route_table_id = aws_route_table.private_regional.id
}

# Security Group for Private Instances
resource "aws_security_group" "private_instances" {
  name        = "private-instances-sg"
  description = "Private Instances Security Group"
  vpc_id      = aws_vpc.main.id

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
    description = "All outbound via Regional NAT"
  }

  tags = { Name = "private-instances-sg" }
}

# Outputs
output "regional_nat_gateway_eip" {
  description = "Regional NAT Gateway Public IP"
  value       = aws_eip.nat.public_ip
}

output "regional_nat_gateway_id" {
  description = "Regional NAT Gateway ID"
  value       = aws_nat_gateway.regional.id
}

output "private_subnet_ids" {
  description = "Private Subnet IDs"
  value       = aws_subnet.private[*].id
}

output "vpc_id" {
  description = "VPC ID"
  value       = aws_vpc.main.id
}

Deploy in 3 Commands

terraform init
terraform plan -out=tfplan
terraform apply tfplan

# Verify NAT Gateway IP
terraform output regional_nat_gateway_eip

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Monitoring & Alarms

Key CloudWatch Metrics

📸 Console Path: CloudWatch → Metrics → NAT Gateway

CloudWatch Alarms - Terraform

resource "aws_cloudwatch_metric_alarm" "nat_bytes_out" {
  alarm_name          = "regional-nat-high-data-usage"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = "2"
  metric_name         = "BytesOutToDestination"
  namespace           = "AWS/NATGateway"
  period              = "3600"
  statistic           = "Sum"
  threshold           = "10737418240" # 10 GB
  alarm_description   = "Alert when NAT Gateway transfers > 10 GB/hour"

  dimensions = {
    NatGatewayId = aws_nat_gateway.regional.id
  }
}

resource "aws_cloudwatch_metric_alarm" "nat_packet_drop" {
  alarm_name          = "regional-nat-packet-drop"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = "1"
  metric_name         = "PacketsDropCount"
  namespace           = "AWS/NATGateway"
  period              = "300"
  statistic           = "Sum"
  threshold           = "0"
  alarm_description   = "Alert on NAT Gateway packet drops"

  dimensions = {
    NatGatewayId = aws_nat_gateway.regional.id
  }
}

VPC Flow Logs

📸 Console Path: VPC → Your VPC → Flow Logs

Destination: CloudWatch Logs
Log group: /aws/vpc/flowlogs
Retention: 7 days

Analyze top traffic sources:

aws logs start-query \
  --log-group-name /aws/vpc/flowlogs \
  --query-string '
    fields srcaddr, bytes
    | filter dstaddr not like "10.0"
    | stats sum(bytes) as total by srcaddr
    | sort total desc
    | limit 10
  '

---

Summary & Decision Guide

Cost Savings Recap

When to Use Regional NAT Gateway

✅ Use Regional NAT When:

• Building new infrastructure
• Cost optimization is priority
• Single egress IP is acceptable
• Want simplified management
• Need multi-AZ redundancy
• Want faster failover (<1 second)
• Need to eliminate cross-AZ charges

⚠️ Use Traditional NAT When:

• Need different IP per AZ for compliance
• Require perfect AZ isolation
• Have vendor IP whitelist requirements per AZ
• Existing architecture with per-AZ dependencies
• Legacy constraints prevent migration

Migration Strategy

For existing infrastructure:

1. Create Regional NAT in one public subnet
2. Update ONE route table to point to Regional NAT
3. Test thoroughly in non-prod first
4. Gradually migrate route table associations
5. Monitor for 2-4 weeks
6. Decommission old NAT Gateways one by one
7. Release unused Elastic IPs

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Key Takeaways

Regional NAT Gateway Benefits:

• 💰 Significant cost reduction vs traditional multi-AZ setup (typically $65.70/month in 3-AZ deployments)
• 🎯 Single NAT serves all AZs automatically
• ⚡ Built-in high availability with automatic failover
• 🚀 Zero cross-AZ data transfer charges
• 📊 Simplified routing (1 route table vs 3+)
• ⏱️ Faster failover (<1 second vs 30-60 seconds)
• 🔑 Single egress IP for easier whitelist management
• 🛠️ Reduced complexity - fewer resources to manage

Real-World Impact (Based on 3-AZ Deployment):

• Potential savings of $800-1,400 annually per environment
• Reduce infrastructure complexity significantly
• Improve failover time by 30-60x
• Eliminate cross-AZ transfer costs for NAT traffic
• Simplify network architecture
• Easier disaster recovery planning

Note: Actual savings depend on your specific infrastructure configuration, region, data transfer volumes, and number of Availability Zones. Use these figures as reference points, not guarantees.

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Additional Resources

• AWS Regional NAT Gateway Documentation
• VPC Best Practices Guide
• NAT Gateway CloudWatch Metrics
• AWS Cost Optimization Guide

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Questions? Share your Regional NAT Gateway experience in the comments! 💬

If this guide saved you money, share it with your team. Happy cloud building! ☁️

Tags: #AWS #CloudArchitecture #NATGateway #Terraform #DevOps #CostOptimization #VPC #CloudInfrastructure