mail3.1gl.ru has no CNAME records.
Question and response
Question
dig mail3.1gl.ru. NS
Answer
The response has no answer records.
Authority
1gl.ru. 300 SOA ns1.fr.ru. internet.action-media.ru. 2022100401 14400 180 2592000 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0