Local load balancers distribute traffic within a datacenter. Global Server Load Balancing (GSLB) distributes traffic across datacenters worldwide.
How it works: GSLB uses DNS to route users to the nearest datacenter.
User in Tokyo → DNS returns Tokyo datacenter IP User in London → DNS returns Frankfurt datacenter IP
Routing strategies:
- Geographic: Route to nearest datacenter
- Latency-based: Route to lowest-latency datacenter
- Failover: Route to backup if primary is down
Cloud providers offer this: AWS Route 53, Google Cloud DNS, Azure Traffic Manager.
Mention GSLB for any system with global users.