mailer.qsupport.ru has no CNAME records.
Question and response
Question
dig mailer.qsupport.ru. NS
Answer
The response has no answer records.
Authority
qsupport.ru. 600 SOA ns01.qdns.ru. it.quantumart.ru. 18480 14400 3600 2592000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0