怎么知道一个域名对应的 IP 是什么？

以 Mac 为例子

1. 打开 iTerm2 （  Mac 终端 or  Windows  终端）
2. dig 域名

dig ucloud.cn


; <<>> DiG 9.10.6 <<>> ucloud.cn
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13175
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;ucloud.cn.            IN    A

;; ANSWER SECTION:
ucloud.cn.        30    IN    A    123.59.130.66

可以看到当前域名 ucloud.cn 直接 A 记录到的 IP 是 123.59.130.66

或者直接用 ping 的方式（但有的情况会被禁 ping)

ping ucloud.cn

PING ucloud.cn (123.59.130.66): 56 data bytes
64 bytes from 123.59.130.66: icmp_seq=0 ttl=43 time=223.814 ms
64 bytes from 123.59.130.66: icmp_seq=1 ttl=43 time=26.982 ms
64 bytes from 123.59.130.66: icmp_seq=2 ttl=43 time=26.473 ms
64 bytes from 123.59.130.66: icmp_seq=3 ttl=43 time=27.259 ms
64 bytes from 123.59.130.66: icmp_seq=4 ttl=43 time=26.994 ms
^C
--- ucloud.cn ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 26.473/66.304/223.814/78.755 ms

也可以看到有返回对应的 IP 地址和统计的延时信息