Apex domains cannot have CNAME records.
Question and response
Question
dig gigaantest01.awk.jp. NS
Answer
gigaantest01.awk.jp. 5 NS ns.gigaantest01.awk.jp.
gigaantest01.awk.jp. 5 NS ns02.xbit.jp.
Authority
The response has no authority records.
Additional
ns.gigaantest01.awk.jp. 5 A 59.106.59.237
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0