Apex domains cannot have CNAME records.
Question and response
Question
dig supercomputingcentres.org. NS
Answer
supercomputingcentres.org. 3 NS dns1.lrz.de.
supercomputingcentres.org. 3 NS dns3.lrz.eu.
supercomputingcentres.org. 3 NS dns2.lrz.bayern.
Authority
The response has no authority records.
Additional
dns1.lrz.de. 2 A 129.187.19.183
dns2.lrz.bayern. 2 A 141.40.9.211
dns3.lrz.eu. 2 A 78.128.211.180
dns1.lrz.de. 2 AAAA 2001:4ca0:0:100:0:53:1:1
dns2.lrz.bayern. 2 AAAA 2001:4ca0:0:100:0:53:1:2
dns3.lrz.eu. 2 AAAA 2001:718:1:1f:50:56ff:feee:180
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0