Apex domains cannot have CNAME records.
Question and response
Question
dig cafe24.com. NS
Answer
cafe24.com. 5 NS ns3.cafe24.com.
cafe24.com. 5 NS nc3.cafe24.com.
cafe24.com. 5 NS nc4.cafe24.com.
cafe24.com. 5 NS ns4.cafe24.com.
Authority
The response has no authority records.
Additional
nc3.cafe24.com. 5 A 1.226.85.3
nc3.cafe24.com. 5 A 1.226.85.6
nc3.cafe24.com. 5 A 1.234.0.3
nc3.cafe24.com. 5 A 1.234.0.6
nc4.cafe24.com. 5 A 1.226.85.2
nc4.cafe24.com. 5 A 1.226.85.5
nc4.cafe24.com. 5 A 1.234.0.2
nc4.cafe24.com. 5 A 1.234.0.5
ns3.cafe24.com. 5 A 112.175.11.2
ns3.cafe24.com. 5 A 112.175.11.5
ns3.cafe24.com. 5 A 112.175.12.2
ns3.cafe24.com. 5 A 112.175.12.5
ns4.cafe24.com. 5 A 112.175.11.3
ns4.cafe24.com. 5 A 112.175.11.6
ns4.cafe24.com. 5 A 112.175.12.3
ns4.cafe24.com. 5 A 112.175.12.6
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0