mx.cittel.ru has no CNAME records.
Question and response
Question
dig mx.cittel.ru. NS
Answer
The response has no answer records.
Authority
cittel.ru. 10800 SOA ns.cittel.ru. hostmaster.cittel.ru. 2026011900 3600 900 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0