Apex domains cannot have CNAME records.
Question and response
Question
dig alida-altemburg.com. NS
Answer
alida-altemburg.com. 4 NS ns-1266.awsdns-30.org.
alida-altemburg.com. 4 NS ns-958.awsdns-55.net.
alida-altemburg.com. 4 NS ns-327.awsdns-40.com.
alida-altemburg.com. 4 NS ns-555.awsdns-05.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0