upstream backend {
    server 1.1.1.1;
    server 1.1.1.2;
}

server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    root /usr/share/nginx/html;
    index index.html index.htm;

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    server_name 1.1.1.3;

    location / {
        proxy_pass http://backend;
    }
}