How to turn off (temporarily) a dedicated server with sites without the consequences of indexing by robots?

Question

Network administration

I want to reinstall the OS, but sites are spinning on the server, how to properly carry out such work so that search robots adequately react to such a situation? Perhaps you need to issue a certain error number, there is access to DNS with TTL 1 minute, you can quickly transfer to another IP server, the main question is what kind of stub to make for this.

Answer 1

Of course, you first need to transfer the dns to another server so that the site responds from there
Put it at the beginning of the server section

server {
return 503;
.........
}

503 Service Temporarily Unavailable is a special code for such cases

Answer 2

Well, pick it up elsewhere and move it, with 503 everything is not so obviously good.