Apex domains cannot have CNAME records.
Question and response
Question
dig bigictfive.uem.mz. NS
Answer
bigictfive.uem.mz. 5 NS oceano.uem.mz.
bigictfive.uem.mz. 5 NS dzowo.uem.mz.
Authority
The response has no authority records.
Additional
dzowo.uem.mz. 172721 A 196.3.96.66
oceano.uem.mz. 172721 A 196.3.96.69
oceano.uem.mz. 3 AAAA 2001:43f8:a40:1:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0