说明：  然后，检查主服务器并基于主服务器的响应的脚本将DNS记录从主服务器交换到备份服务器。如果...，
(Script that checks main server and based on the response of main server will then swap DNS records from main server to backup server. If a swap occurs, the script will message administrator and check main server status on regular intervals. Once main server is back up the script will swap DNS records back to main server and message administrator.)