mail.lan.com.ua has no CNAME records.
Question and response
Question
dig mail.lan.com.ua. NS
Answer
The response has no answer records.
Authority
lan.com.ua. 3369 SOA nsa2.srv53.net. support.dnshosting.org. 1701363903 1800 600 2419200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0