mail.kool.bcs.ee has no CNAME records.
Question and response
Question
dig mail.kool.bcs.ee. NS
Answer
The response has no answer records.
Authority
bcs.ee. 1616 SOA ns.elkdata.ee. hostmaster.ns.elkdata.ee. 2026021801 10800 1800 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0