1. whois
$ dig -t ns irasutoya.com @a.gtld-servers.net
irasutoya.com. 172800 IN NS ns1.value-domain.com. irasutoya.com. 172800 IN NS ns2.value-domain.com. irasutoya.com. 172800 IN NS ns3.value-domain.com. irasutoya.com. 172800 IN NS ns4.value-domain.com. irasutoya.com. 172800 IN NS ns5.value-domain.com. irasutoya.com. 1200 IN CNAME ghs.google.com.