mail.gin.ntt.net has no CNAME records.
Question and response
Question
dig mail.gin.ntt.net. NS
Answer
The response has no answer records.
Authority
gin.ntt.net. 147 SOA ipam01.dllstx09.us.to.gin.ntt.net. dns-tech.gin.ntt.net. 2021062912 86400 3600 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0