1、先用nslookup获得域名对应的主机ip：nslookup 域名
2、再根据主机ip获得对应的主机名称： host ip
$ nslookup baidu.com
Server: 127.0.1.1
Address: 127.0.1.1# Non-authoritative answer:
Name: baidu.com
Address: 39.156.69.79
Name: baidu.com
Address: 220.181.38.148
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$ host 39.156.69.79
Host 79.69.156.39.in-addr.arpa. not found: (NXDOMAIN)