Apex domains cannot have CNAME records.
Question and response
Question
dig ciuem.mz. NS
Answer
ciuem.mz. 5 NS oceano.uem.mz.
ciuem.mz. 5 NS dzowo.uem.mz.
ciuem.mz. 5 NS zebra.uem.mz.
Authority
The response has no authority records.
Additional
dzowo.uem.mz. 125730 A 196.3.96.66
zebra.uem.mz. 86501 A 196.3.96.67
oceano.uem.mz. 156505 A 196.3.96.69
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0