Apex domains cannot have CNAME records.
Question and response
Question
dig wavemail.com. NS
Answer
wavemail.com. 5 NS ns3.waveip.org.
wavemail.com. 5 NS ns2.waveip.org.
wavemail.com. 5 NS ns1.waveip.org.
wavemail.com. 5 NS ns4.waveip.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0