Apex domains cannot have CNAME records.
Question and response
Question
dig seppmail247.com. NS
Answer
seppmail247.com. 5 NS ns1.itmuller.com.
seppmail247.com. 5 NS ns2.itmuller.com.
seppmail247.com. 5 NS ns1.itmnetx.com.
seppmail247.com. 5 NS ns2.itmnetx.com.
Authority
The response has no authority records.
Additional
ns1.itmnetx.com. 1 AAAA 2001:4178:3:a357:62:116:159:4
ns1.itmuller.com. 1 AAAA 2001:8d8:580:401:217:160:113:37
ns2.itmnetx.com. 1 AAAA 2a01:130:2000:118:89:146:248:4
ns2.itmuller.com. 1 AAAA 2607:f1c0:1800:8091:74:208:254:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0