Apex domains cannot have CNAME records.
Question and response
Question
dig cefid.edu.do. NS
Answer
cefid.edu.do. 5 NS ns1.contabo.net.
cefid.edu.do. 5 NS ns2.contabo.net.
cefid.edu.do. 5 NS ns3.contabo.net.
Authority
The response has no authority records.
Additional
ns1.contabo.net. 1 A 5.180.150.13
ns2.contabo.net. 1 A 195.179.224.10
ns3.contabo.net. 1 A 209.126.15.15
ns1.contabo.net. 1 AAAA 2a02:c207:ff00:1200:0:0:0:1
ns2.contabo.net. 1 AAAA 2a02:c202:5028:1200:0:0:0:1
ns3.contabo.net. 1 AAAA 2605:a140:5028:1200:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0