执行以下命令：
yum install bind-utils
例子：
dig www.baidu.com
; <<>> DiG 9.9.4-RedHat-9.9.4-38.el7_3.1 <<>> www.baidu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57861
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 5, ADDITIONAL: 6
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.baidu.com. IN A
;; ANSWER SECTION:
www.baidu.com. 309 IN CNAME www.a.shifen.com.
www.a.shifen.com. 198 IN A 61.135.169.121
www.a.shifen.com. 198 IN A 61.135.169.125
;; AUTHORITY SECTION:
a.shifen.com. 1198 IN NS ns4.a.shifen.com.
a.shifen.com. 1198 IN NS ns5.a.shifen.com.
a.shifen.com. 1198 IN NS ns2.a.shifen.com.
a.shifen.com. 1198 IN NS ns3.a.shifen.com.
a.shifen.com. 1198 IN NS ns1.a.shifen.com.
;; ADDITIONAL SECTION:
ns1.a.shifen.com. 1198 IN A 61.135.165.224
ns2.a.shifen.com. 1198 IN A 180.149.133.241
ns3.a.shifen.com. 1198 IN A 61.135.162.215
ns4.a.shifen.com. 1198 IN A 115.239.210.176
ns5.a.shifen.com. 1198 IN A 119.75.222.17
;; Query time: 0 msec
;; SERVER: 198.18.254.30#53(198.18.254.30)
;; WHEN: Mon Feb 20 20:26:12 CST 2017
;; MSG SIZE rcvd: 271