Apex domains cannot have CNAME records.
Question and response
Question
dig accellion.com. NS
Answer
accellion.com. 4 NS dnsus1.accellion.com.
accellion.com. 4 NS dnsus2.accellion.com.
accellion.com. 4 NS dnsma.accellion.com.
Authority
The response has no authority records.
Additional
dnsma.accellion.com. 4 A 18.207.87.206
dnsus1.accellion.com. 4 A 174.129.192.189
dnsus2.accellion.com. 4 A 174.129.8.146
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0