Apex domains cannot have CNAME records.
Question and response
Question
dig xvserver.com. NS
Answer
xvserver.com. 5 NS ns2.xvserver.com.
xvserver.com. 5 NS ns1.xvserver.com.
Authority
The response has no authority records.
Additional
ns1.xvserver.com. 5 A 190.105.228.200
ns2.xvserver.com. 5 A 107.6.16.14
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0