One address, many locations.
WHAT IT IS
The same address announced from several locations, with routing directing each user to the nearest.
WHAT NEAREST MEANS
Nearest by routing policy, which is not necessarily nearest geographically.
WHAT IT PROVIDES
Lower latency, since the path is shorter Load distribution, without a load balancer Resilience, since a failed location stops announcing and traffic moves Absorption of volumetric attacks, spread across locations
WHAT IT SUITS
Naming services Content delivery Any stateless service where any location can serve any request
WHAT IT DOES NOT SUIT
Long-lived connections requiring the same endpoint, unless handled carefully.
WHY
A routing change mid-connection can move a user to a different location.
WHAT MITIGATES THAT
Modern transport protocols that survive path changes, and careful session handling.
WHAT IT REQUIRES
Address space you control The ability to announce from several locations Consistent service at every location
WHAT TO MONITOR
Which location users actually reach, from several vantage points.
WHY
Routing decides, and the result frequently surprises.
