Apex domains cannot have CNAME records.
Question and response
Question
dig speedlimitunder7.com. NS
Answer
speedlimitunder7.com. 5 NS ns2.speedlimitunder7.com.
speedlimitunder7.com. 5 NS ns1.speedlimitunder7.com.
Authority
The response has no authority records.
Additional
ns1.speedlimitunder7.com. 5 A 192.3.185.60
ns2.speedlimitunder7.com. 5 A 78.135.109.38
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0