ns4.dnsrubycom.com has no CNAME records.
Question and response
Question
dig ns4.dnsrubycom.com. NS
Answer
The response has no answer records.
Authority
dnsrubycom.com. 550 SOA ns07.domaincontrol.com. dns.jomax.net. 2025042509 28800 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0