ns2.seo.r1servers.com has no CNAME records.
Question and response
Question
dig ns2.seo.r1servers.com. NS
Answer
The response has no answer records.
Authority
seo.r1servers.com. 4240 SOA ns1.seo.r1servers.com. office.hostbulgaria.com. 2026022301 86400 7200 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0