Apex domains cannot have CNAME records.
Question and response
Question
dig mdtdepot.com. NS
Answer
mdtdepot.com. 4 NS ns1508.ztomy.com.
mdtdepot.com. 4 NS ns2508.ztomy.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0