Apex domains cannot have CNAME records.
Question and response
Question
dig thryv.com. NS
Answer
thryv.com. 1 NS ns1.thryvinc-ns.com.
thryv.com. 1 NS ns2.thryvinc-ns.com.
thryv.com. 1 NS ns3.thryvinc-ns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0