300ms to 50ms: Solving Global Latency with AWS CloudFront, Global Accelerator, and Route 53 - Dev.

If you have ever deployed a "global" application with a single region backend, you know the pain. Users in Tokyo hitting an API in N. Virginia (us-east-1) face unpredictable jitter, packet loss, and latency hovering around 250-300ms. The public internet's BGP routing is notoriously inefficient for long-haul traffic. In a recent high-traffic financial platform migration, we faced exactly this bottleneck. The solution wasn't just "adding more servers"; it required a precise architectural blend of aws networking services to bypass the public internet and leverage the AWS private backbone.

Why DNS Alone Isn't Enough

Many engineers start by tweaking Route 53 policies, hoping Latency-Based Routing (LBR) will solve the issue. While Route 53 effectively steers a user to the closest endpoint, it cannot speed up the packets once they leave the user's device. If your backend is centralized, steering a user in London to a US server via standard internet routing still results in multiple hops across public ISPs.

The Core Problem: The TCP handshake over long distances is expensive. For an HTTPS connection, the round-trip time (RTT) penalties stack up during the TLS negotiation, making the application feel sluggish regardless of server power.

To solve this, we need to terminate the connection closer to the user. This is where the distinction between static and dynamic content acceleration becomes critical:

• CloudFront: Best for static assets (images, CSS, JS) and read-heavy APIs where caching is acceptable. It moves content to the Edge.
• Global Accelerator: Critical for dynamic, non-cacheable TCP/UDP traffic (like WebSocket or write-heavy REST APIs). It ingests traffic at the Edge and rides the AWS backbone to the origin.

The Hybrid Architecture: Terraform Implementation

The most robust pattern involves using Route 53 as the intelligent entry point, delegating static requests to CloudFront and dynamic API calls to Global Accelerator. This split-horizon approach maximizes cache hit rates while ensuring transactional integrity for API calls.

Here is a Terraform snippet demonstrating how to set up a Global Accelerator listener that forwards traffic to an Application Load Balancer (ALB), bypassing the public internet path.

resource "aws_globalaccelerator_accelerator" "main" {
  name            = "api-accelerator"
  ip_address_type = "IPV4"
  enabled         = true

  attributes {
    flow_logs_enabled   = true
    flow_logs_s3_bucket = "logs-bucket"
    flow_logs_s3_prefix = "flow-logs/"
  }
}

resource "aws_globalaccelerator_listener" "https" {
  accelerator_arn = aws_globalaccelerator_accelerator.main.id
  client_affinity = "NONE" // Use SOURCE_IP if session stickiness is needed
  protocol        = "TCP"

  port_range {
    from_port = 443
    to_port   = 443
  }
}

resource "aws_globalaccelerator_endpoint_group" "us_east_1" {
  listener_arn = aws_globalaccelerator_listener.https.id
  endpoint_group_region = "us-east-1"

  endpoint_configuration {
    // Pointing to the internal ALB
    endpoint_id = aws_lb.backend_alb.arn
    weight      = 100
  }
}

// Route 53 Alias Record pointing to Global Accelerator
resource "aws_route53_record" "api" {
  zone_id = aws_route53_zone.primary.zone_id
  name    = "api.example.com"
  type    = "A"

  alias {
    name                   = aws_globalaccelerator_accelerator.main.dns_name
    zone_id                = aws_globalaccelerator_accelerator.main.hosted_zone_id
    evaluate_target_health = true
  }
}

Security Note: When using Global Accelerator, your ALB security groups must allow traffic from the Global Accelerator health check IP ranges, not just the open internet. Neglecting this often leads to failed health checks during deployment.

Real-World Performance Comparison

We conducted a benchmark measuring the Time to First Byte (TTFB) from a client in Singapore connecting to a backend in N. Virginia. The difference emphasizes the stability of the AWS backbone versus the public internet.

Routing Method	Avg Latency (ms)	Packet Loss (%)	Jitter (ms)
Public Internet (Standard DNS)	280ms	1.5%	±45ms
Route 53 + CloudFront (Cached)	15ms	0%	±2ms
Global Accelerator (Dynamic)	190ms	<0.1%	±5ms

By utilizing the AWS global network, we stabilize the latency. While the speed of light limits the minimum RTT, the removal of jitter and packet loss creates a significantly snappier user experience.

Conclusion

Latency is not just a networking metric; it is a direct revenue blocker. Relying solely on the public internet for global traffic is a gamble you don't need to take. By strategically layering CloudFront for static assets, Global Accelerator for reliable ingress, and Route 53 for intelligent DNS resolution, you create a robust entry path for your users. Start with the Global Accelerator implementation shown above for your critical API endpoints and observe the immediate drop in P99 latency metrics.