Apex domains cannot have CNAME records.
Question and response
Question
dig cap.edu.do. NS
Answer
cap.edu.do. 5 NS ns3.wordpress.com.
cap.edu.do. 5 NS ns2.wordpress.com.
cap.edu.do. 5 NS ns1.wordpress.com.
Authority
The response has no authority records.
Additional
ns1.wordpress.com. 5 A 198.181.116.9
ns2.wordpress.com. 5 A 198.181.117.9
ns3.wordpress.com. 5 A 192.0.74.9
ns1.wordpress.com. 5 AAAA 2a04:fa87:ffff:0:0:0:c6b5:7409
ns2.wordpress.com. 5 AAAA 2a04:fa87:ffff:0:0:0:c6b5:7509
ns3.wordpress.com. 5 AAAA 2620:115:c00f:0:0:0:c000:4a09
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0