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