IANANetwork Engineer but basically with anycasting you can announce a single IP from two different places and different providers will route to whichever is 'cl

IANANetwork Engineer but basically with anycasting you can announce a single IP from two different places and different providers will route to whichever is 'closest'. If your datacenter goes down one of those routes stops being advertised and providers will re-route to the next best advertised route. BGP cycle time is variable but way less than 30 minutes in many cases. This presumes you can essentially have two 'active' datacenters, not all application designs allow for this. You can still use BGP as a failover mechanism, just announce the route to your production IP from DC1 and if that dies, announce it from DC2 once you fail over. Again, limited by response time and BGP cycle time but that's faster than DNS.