mx3.bit.org has no CNAME records.
Question and response
Question
dig mx3.bit.org. NS
Answer
The response has no answer records.
Authority
bit.org. 5136 SOA ns1.rrpproxy.net. tech.rrpproxy.net. 2025105744 10800 3600 604800 28800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0