Apex domains cannot have CNAME records.
Question and response
Question
dig trendmicro.com. NS
Answer
trendmicro.com. 5 NS a3-66.akam.net.
trendmicro.com. 5 NS a24-65.akam.net.
trendmicro.com. 5 NS a22-66.akam.net.
trendmicro.com. 5 NS a18-64.akam.net.
trendmicro.com. 5 NS a1-159.akam.net.
trendmicro.com. 5 NS a5-67.akam.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0