Apex domains cannot have CNAME records.
Question and response
Question
dig elsa.ccn-cert.net. NS
Answer
elsa.ccn-cert.net. 5 NS ns-378.awsdns-47.com.
elsa.ccn-cert.net. 5 NS ns-1463.awsdns-54.org.
elsa.ccn-cert.net. 5 NS ns-631.awsdns-14.net.
elsa.ccn-cert.net. 5 NS ns-1919.awsdns-47.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0