Apex domains cannot have CNAME records.
Question and response
Question
dig eaqa1.connectalk.com. NS
Answer
eaqa1.connectalk.com. 5 NS ns.ctalk.com.
eaqa1.connectalk.com. 5 NS ns3.connectalk.com.
eaqa1.connectalk.com. 5 NS ns2.connectalk.com.
Authority
The response has no authority records.
Additional
ns.ctalk.com. 5 A 204.19.165.1
ns2.connectalk.com. 5 A 204.19.165.78
ns3.connectalk.com. 5 A 192.172.250.42
ns.ctalk.com. 5 AAAA 2607:fad8:1100:0:0:0:1:1
ns2.connectalk.com. 5 AAAA 2607:fad8:1100:10dc:0:0:0:3
ns3.connectalk.com. 5 AAAA 2607:2a00:2:0:0:0:c0ac:fa2a
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0