Is it possible to set up an emergency redirect to another hosting via DNS if the first one is down?

Question

Domain Name System

Hello, I came across such a service from a dns provider - Failover Records, the service redirects traffic to a copy of the resource, if the main server is down, I had a theoretical question, how is this implemented, because records need to be distributed, doesn’t it need about a day? Or is it still possible to implement instant switching, and you need to take this service?

Answer 1

Keywords - "redirects traffic".
If this is done in a smart way, then all HTTP(S) incoming traffic is simply redirected to the "spare" IP address.
The DNS record does not change, and the traffic still goes to the original IP address of the downed server.
And yet, DNS records have a "update time" after which the record is updated. And there you can specify at least 10 minutes.

Answer 2

Nothing prevents the provider from setting the TTL of the record for a few seconds. At the same time, it will practically not be cached on intermediate servers.