Apex domains cannot have CNAME records.
Question and response
Question
dig regroup.com. NS
Answer
regroup.com. 3 NS ns-1458.awsdns-54.org.
regroup.com. 3 NS ns-595.awsdns-10.net.
regroup.com. 3 NS ns-290.awsdns-36.com.
regroup.com. 3 NS ns-1688.awsdns-19.co.uk.
Authority
The response has no authority records.
Additional
ns-290.awsdns-36.com. 2 A 205.251.193.34
ns-595.awsdns-10.net. 2 A 205.251.194.83
ns-1458.awsdns-54.org. 2 A 205.251.197.178
ns-1688.awsdns-19.co.uk. 2 A 205.251.198.152
ns-290.awsdns-36.com. 2 AAAA 2600:9000:5301:2200:0:0:0:1
ns-595.awsdns-10.net. 2 AAAA 2600:9000:5302:5300:0:0:0:1
ns-1458.awsdns-54.org. 2 AAAA 2600:9000:5305:b200:0:0:0:1
ns-1688.awsdns-19.co.uk. 2 AAAA 2600:9000:5306:9800:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0