下载适用于 Linux/Mac/Windows 的免费 Nmap 安全扫描程序
nmap.exe -sU -p53 223.6.6.6
出现下方open字样为连通状态
Starting Nmap 7.92 ( https://nmap.org ) at 2000-08-09 11:48 中国标准时间 Nmap scan report for public2.alidns.com (223.6.6.6) Host is up (0.0033s latency).
PORT STATE SERVICE 53/udp open domain Nmap done: 1 IP address (1 host up) scanned in 0.29 seconds