Apex domains cannot have CNAME records.
Question and response
Question
dig seoplushost.com. NS
Answer
seoplushost.com. 5 NS ns1.seoplushost.com.
seoplushost.com. 5 NS ns2.seoplushost.com.
Authority
The response has no authority records.
Additional
ns1.seoplushost.com. 5 A 52.26.173.181
ns2.seoplushost.com. 5 A 52.26.173.181
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0