What is anycast addressing (IPv6)?

Anycast is one-to-nearest: the same address is assigned to multiple devices, and routing delivers traffic to the closest instance. It is built into IPv6.

* Anycast: many devices share one address; routing picks the closest. *

An anycast address is assigned to multiple devices, and traffic goes to the closest one.

How it works:

1. Same IP address configured on multiple servers
2. Network routing directs traffic to nearest server
3. Client connects to geographically closest instance

Use cases:

• DNS root servers
• CDN (Content Delivery Networks)
• Load balancing

IPv6 feature:

• Built into IPv6 design
• IPv4 can simulate with BGP tricks

Memory tip: Anycast = "ANY of these will do, pick the closest!"

Go deeper:

• Anycast — one-address-many-servers routing, used by DNS root servers and CDNs.