Apex domains cannot have CNAME records.
Question and response
Question
dig flexential.com. NS
Answer
flexential.com. 3 NS ns6.peak10.com.
flexential.com. 3 NS ns1.peak10.com.
flexential.com. 3 NS ns2.peak10.com.
flexential.com. 3 NS ns3.peak10.com.
flexential.com. 3 NS ns4.peak10.com.
flexential.com. 3 NS ns5.peak10.com.
Authority
The response has no authority records.
Additional
ns1.peak10.com. 3 A 156.154.64.1
ns2.peak10.com. 3 A 156.154.65.1
ns3.peak10.com. 3 A 156.154.66.1
ns4.peak10.com. 3 A 156.154.67.1
ns5.peak10.com. 3 A 156.154.68.1
ns6.peak10.com. 3 A 156.154.69.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0