Apex domains cannot have CNAME records.
Question and response
Question
dig ng.telekom.net. NS
Answer
ng.telekom.net. 5 NS ns-1195.awsdns-21.org.
ng.telekom.net. 5 NS ns-1885.awsdns-43.co.uk.
ng.telekom.net. 5 NS ns-185.awsdns-23.com.
ng.telekom.net. 5 NS ns-550.awsdns-04.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0