ns3.mailkit.net has no CNAME records.
Question and response
Question
dig ns3.mailkit.net. NS
Answer
The response has no answer records.
Authority
mailkit.net. 1390 SOA ns1.mailkit.net. postmaster.mailkit.net. 2026030501 28800 300 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0