Apex domains cannot have CNAME records.
Question and response
Question
dig co.mz. NS
Answer
co.mz. 5 NS dzowo.uem.mz.
co.mz. 5 NS phloem.uoregon.edu.
co.mz. 5 NS anyns.uem.mz.
co.mz. 5 NS oceano.uem.mz.
co.mz. 5 NS ns-mz.afrinic.net.
co.mz. 5 NS zebra.uem.mz.
Authority
The response has no authority records.
Additional
anyns.uem.mz. 91764 A 204.61.216.14
dzowo.uem.mz. 172494 A 196.3.96.66
zebra.uem.mz. 172494 A 196.3.96.67
oceano.uem.mz. 172494 A 196.3.96.69
phloem.uoregon.edu. 5 A 128.223.32.35
oceano.uem.mz. 2 AAAA 2001:43f8:a40:1:0:0:0:2
phloem.uoregon.edu. 5 AAAA 2001:468:d01:20:0:0:80df:2023
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0