1. whois
tmaeno@conoha:~/jp/at/ns$ dig -t ns icop.co.jp @202.224.239.137 ;; communications error to 202.224.239.137#53: timed out ;; communications error to 202.224.239.137#53: timed out ;; communications error to 202.224.239.137#53: timed out ; <<>> DiG 9.18.12-0ubuntu0.22.04.1-Ubuntu <<>> -t ns icop.co.jp @202.224.239.137 ;; global options: +cmd ;; no servers could be reached
2. history
icop.co.jp. 86400 IN NS ns.dmp.com.tw. icop.co.jp. 86400 IN NS ns.icop.co.jp. ;; ADDITIONAL SECTION: ns.icop.co.jp. 86400 IN A 202.224.239.137
ns.icop.co.jp 119.245.129.106
$ dig -t ns icop.co.jp +nocookie @119.245.129.106 ;; communications error to 119.245.129.106#53: timed out ;; communications error to 119.245.129.106#53: timed out ;; communications error to 119.245.129.106#53: timed out ; <<>> DiG 9.18.12-0ubuntu0.22.04.1-Ubuntu <<>> -t ns icop.co.jp +nocookie @119.245.129.106 ;; global options: +cmd ;; no servers could be reached