BGP Anycast (possibly in combination with DNS depending on geolocation). Basically you announce the same IP address from multiple locations, and BGP chooses th

BGP Anycast (possibly in combination with DNS depending on geolocation). Basically you announce the same IP address from multiple locations, and BGP chooses the best* Route to reach that address. * Note that "best" does not nessecarily mean "fastest", not even "least hops" - BGP has many knobs where the routing decisions can be manipulated, but by default it choses the route where traffic has to traverse the smallest number of "Autonomous Systems" (roughly equivalent to "Organizational Entities").