Apex domains cannot have CNAME records.
Question and response
Question
dig os-ns.com. NS
Answer
os-ns.com. 4 NS n2.os-ns.com.
os-ns.com. 4 NS n1.os-ns.com.
Authority
The response has no authority records.
Additional
n1.os-ns.com. 4 A 190.183.223.110
n2.OS-NS.COM. 4 A 190.105.144.15
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0