mG.g-cloud.by has no CNAME records.
Question and response
Question
dig mG.g-cloud.by. NS
Answer
The response has no answer records.
Authority
g-cloud.by. 4883 SOA ns1.g-cloud.by. tech.g-cloud.by. 2018117146 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0