DNS Caching Issue For community version

[RT.Nat]

I wanted check whether the resolver solves the DNS in a dynamic manner when
the ip addresses changes.

So I add the given code after several findings and yet the resolving the ip
address is not happening.

server{
...........

resolver 8.8.8.8 valid=30s;
resolver_timeout 10s;
set $upstream "example.net";

location / {
                rewrite ^/(.*) /$1 break;
                proxy_pass https://$upstream:3000;
            

        }

}

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,266857,266862#msg-266862