Apex domains cannot have CNAME records.
Question and response
Question
dig loopinternet.com. NS
Answer
loopinternet.com. 3 NS ns-1502.awsdns-59.org.
loopinternet.com. 3 NS ns-292.awsdns-36.com.
loopinternet.com. 3 NS ns-895.awsdns-47.net.
loopinternet.com. 3 NS ns-1626.awsdns-11.co.uk.
Authority
The response has no authority records.
Additional
ns-895.awsdns-47.net. 1 A 205.251.195.127
ns-1502.awsdns-59.org. 1 A 205.251.197.222
ns-1626.awsdns-11.co.uk. 1 A 205.251.198.90
ns-292.awsdns-36.com. 1 AAAA 2600:9000:5301:2400:0:0:0:1
ns-895.awsdns-47.net. 1 AAAA 2600:9000:5303:7f00:0:0:0:1
ns-1502.awsdns-59.org. 1 AAAA 2600:9000:5305:de00:0:0:0:1
ns-1626.awsdns-11.co.uk. 1 AAAA 2600:9000:5306:5a00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0