Apex domains cannot have CNAME records.
Question and response
Question
dig gslb.kcom.com. NS
Answer
gslb.kcom.com. 5 NS lb2.civ.scp.kcom.com.
gslb.kcom.com. 5 NS lb2.kir.scp.kcom.com.
gslb.kcom.com. 5 NS lb1.civ.scp.kcom.com.
gslb.kcom.com. 5 NS lb1.kir.scp.kcom.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0