Uninterrupted operation of the site in the event of a server crash?

Question

High availability

There is a server, there is always the possibility of shutting down the server for some reason. How can I balance the site between the main and backup server? For example: the main server stopped responding, so you need to open it from a backup server. Are there any DNS servers for this purpose?

Answer 1

This is called Round Robin DNS.
https://ru.m.wikipedia.org/wiki/Round_robin_DNS

Answer 2

2 servers + balancer