primaryns.dnb.com has no MX records.
Question and response
Question
dig primaryns.dnb.com. MX
Answer
The response has no answer records.
Authority
dnb.com. 3600 SOA primaryns.dnb.com. dnsadmin.dnb.com. 2021084939 1200 600 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0