Apex domains cannot have CNAME records.
Question and response
Question
dig singlehop.com. NS
Answer
singlehop.com. 5 NS ns1.singlehop.com.
singlehop.com. 5 NS ns3.singlehop.com.
singlehop.com. 5 NS ns2.singlehop.com.
Authority
The response has no authority records.
Additional
ns1.singlehop.com. 5 A 184.154.3.28
ns2.singlehop.com. 5 A 184.154.3.29
ns3.singlehop.com. 5 A 184.154.3.39
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0