Apex domains cannot have CNAME records.
Question and response
Question
dig mtntel.net. NS
Answer
mtntel.net. 3 NS nsx.integraonline.com.
mtntel.net. 3 NS nsy.integraonline.com.
Authority
The response has no authority records.
Additional
nsx.integraonline.com. 3 A 67.50.245.2
nsy.integraonline.com. 3 A 67.50.245.101
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0