[root@centos7 ~]# dig google.com
; <<>> DiG 9.9.4-RedHat-9.9.4-29.el7_2.3 <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25853
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;google.com. IN A
;; ANSWER SECTION:
google.com. 196 IN A 216.58.197.206
;; Query time: 45 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Wed May 31 22:19:09 JST 2017
;; MSG SIZE rcvd: 55
[root@centos7 ~]#
[user01@centos7 ~]$ dig google.com | grep ^google.com
google.com. 287 IN A 172.217.26.46
[user01@centos7 ~]$
[user01@centos7 ~]$
[user01@centos7 ~]$ dig google.com | grep ^google.com
google.com. 285 IN A 172.217.26.46
[user01@centos7 ~]$
[user01@centos7 ~]$ dig google.com | grep ^google.com
google.com. 284 IN A 172.217.26.46
[user01@centos7 ~]$
[user01@centos7 ~]$ while : ; do echo -n "`date ` : " ; dig google.com | grep ^google.com ; sleep 1 ; done
Wed May 24 20:12:16 JST 2017 : google.com. 164 IN A 172.217.26.46
Wed May 24 20:12:17 JST 2017 : google.com. 163 IN A 172.217.26.46
Wed May 24 20:12:18 JST 2017 : google.com. 161 IN A 172.217.26.46
Wed May 24 20:12:19 JST 2017 : google.com. 160 IN A 172.217.26.46
Wed May 24 20:12:20 JST 2017 : google.com. 159 IN A 172.217.26.46
Wed May 24 20:12:21 JST 2017 : google.com. 158 IN A 172.217.26.46
^C
DNS