Apex domains cannot have CNAME records.
Question and response
Question
dig 107.234.109.in-addr.arpa. NS
Answer
107.234.109.in-addr.arpa. 5 NS ns.skywaydc.net.
107.234.109.in-addr.arpa. 5 NS ns.skywaydc.com.
107.234.109.in-addr.arpa. 5 NS ns.skywaydc.de.
Authority
The response has no authority records.
Additional
ns.skywaydc.de. 5 A 193.227.117.225
ns.skywaydc.com. 5 A 194.50.187.225
ns.skywaydc.net. 5 A 194.0.182.225
ns.skywaydc.de. 5 AAAA 2a04:2b00:14cc:0:0:0:0:225
ns.skywaydc.com. 5 AAAA 2a04:2b00:14dd:0:0:0:0:225
ns.skywaydc.net. 5 AAAA 2a04:2b00:14ee:0:0:0:0:225
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0