smtp00.messageflow.com has no NS records.
NS records for this zone are defined at messageflow.com.
NS records for this zone are defined at messageflow.com.
Question and response
Question
dig smtp00.messageflow.com. NS
Answer
The response has no answer records.
Authority
messageflow.com. 1800 SOA athena.ns.cloudflare.com. dns.cloudflare.com. 2397753105 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0