Global Accelerator — Concept
What it is
AWS Global Accelerator = a network service that gives your app two static anycast IPs at the AWS edge and routes traffic to the optimal AWS region over the AWS global backbone — for any TCP or UDP traffic.
Why it exists
- CloudFront is for HTTP/HTTPS caching at edge.
- Route 53 latency policy depends on DNS TTL and resolver behavior → slow failover.
Global Accelerator solves: multi-region active-active or active-passive for non-HTTP workloads (gaming, VoIP, IoT, Multiplayer, financial apps) with fast failover and stable IPs.
How it works
- Create an Accelerator → AWS assigns 2 static anycast IPv4 addresses (or bring your own IP, BYOIP).
- Add Listeners for ports/protocols (TCP, UDP).
- Add Endpoint Groups per region.
- Add Endpoints in each group (ALB, NLB, EC2, EIP).
- Users hit the nearest edge POP → traffic enters the AWS backbone → routed to the healthiest, closest endpoint.
Traffic controls
- Traffic Dial per endpoint group (% weight, e.g. shift 0 → drain a region).
- Endpoint Weight within a group.
- Health checks per endpoint; unhealthy region pulled within seconds.
- Client affinity = stick a client to one endpoint by source IP (source IP + port option also).
CloudFront vs Global Accelerator (exam favorite)
| CloudFront | Global Accelerator | |
|---|---|---|
| Protocol | HTTP / HTTPS only | TCP / UDP (any) |
| Caching | Yes | No |
| IPs | DNS-based | 2 static anycast IPs |
| Use | Web, static assets | Gaming, real-time, non-HTTP, IP whitelist required |
| Failover | DNS-driven | Seconds via health checks |
| Integrates with | S3, ALB, EC2 | ALB, NLB, EC2, EIP |
When to use vs alternatives
| Need | Use |
|---|---|
| Web app, static + dynamic, caching | CloudFront |
| TCP/UDP game / VoIP / IoT, multi-region | Global Accelerator |
| Static IP needed for partner whitelisting | Global Accelerator |
| Fast failover between regions, < DNS TTL | Global Accelerator |
| Pure DNS routing | Route 53 latency / failover |
Common exam scenarios
- "Mobile game with UDP traffic, players worldwide, low latency" → Global Accelerator.
- "Two static IPs partners can whitelist, backed by ALBs in 3 regions" → Global Accelerator.
- "Active-passive multi-region failover in seconds for a TCP API" → Global Accelerator (Route 53 failover relies on DNS TTL).
- "Static site with caching for global users" → CloudFront (not Global Accelerator).
- "VoIP traffic with consistent latency" → Global Accelerator uses AWS backbone end-to-end.
Exam tip
HTTP only / caching → CloudFront. TCP/UDP, static IPs, fast failover, multi-region for non-web → Global Accelerator. They are not substitutes; sometimes you use both.