Why Your Website Loads Fast Everywhere — Thanks to Anycast

Source: Dev.to

What Is Anycast?

Anycast is a network addressing technique where multiple servers in different global locations all advertise the same IP address into the routing system (usually via BGP).

Your router then selects the “nearest” server based on:

• Lowest latency
• Shortest AS path
• Routing policy preference

👉 Anycast = one single IP address served by multiple servers across the world.

How Anycast Actually Works (BGP Magic)

Behind the scenes, BGP makes Anycast possible. Here’s the flow:

1. Advertise the Anycast prefix — each PoP (Point of Presence) pushes the IP via BGP/OSPF.
2. Routing picks the winner — global routers calculate path cost and forward packets to the closest location.
3. Failover happens automatically — if a PoP (e.g., in India) goes down, it withdraws the BGP route, and traffic shifts instantly.

Client → ISP → Internet backbone → Nearest Anycast node

• No DNS changes
• No user action
• No downtime

Unicast vs. Anycast

• Unicast = every customer must go to one original branch.
• Anycast = customers are automatically routed to the nearest branch of the same service (like the nearest restaurant location).

Further Reading

🔗 Want the full breakdown? Check out the complete blog post:
The Hidden Internet Superpower: How Anycast + BGP Make Websites Faster and Unstoppable