Apex domains cannot have CNAME records.
Question and response
Question
dig org.mz. NS
Answer
org.mz. 5 NS anyns.uem.mz.
org.mz. 5 NS phloem.uoregon.edu.
org.mz. 5 NS ns-mz.afrinic.net.
org.mz. 5 NS zebra.uem.mz.
org.mz. 5 NS oceano.uem.mz.
org.mz. 5 NS dzowo.uem.mz.
Authority
The response has no authority records.
Additional
anyns.uem.mz. 135835 A 204.61.216.14
dzowo.uem.mz. 135835 A 196.3.96.66
zebra.uem.mz. 94643 A 196.3.96.67
oceano.uem.mz. 164717 A 196.3.96.69
phloem.uoregon.edu. 3 A 128.223.32.35
phloem.uoregon.edu. 3 AAAA 2001:468:d01:20:0:0:80df:2023
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0