mail.itcom.info has no CNAME records.
Question and response
Question
dig mail.itcom.info. NS
Answer
The response has no answer records.
Authority
itcom.info. 2845 SOA isp.24hc.ru. info.itcom.info. 2017052294 3600 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0