Apex domains cannot have CNAME records.
Question and response
Question
dig suumo.com. NS
Answer
suumo.com. 4 NS ns2.x.recruit.co.jp.
suumo.com. 4 NS ns1.x.recruit.co.jp.
suumo.com. 4 NS ns3.x.recruit.co.jp.
Authority
The response has no authority records.
Additional
ns1.x.recruit.co.jp. 4 A 160.17.13.6
ns2.x.recruit.co.jp. 4 A 160.17.13.7
ns3.x.recruit.co.jp. 4 A 160.17.13.8
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0