mx1.payone.com has no NS records.
NS records for this zone are defined at payone.com.
NS records for this zone are defined at payone.com.
Question and response
Question
dig mx1.payone.com. NS
Answer
The response has no answer records.
Authority
payone.com. 300 SOA ns-cloud-a1.googledomains.com. cloud-dns-hostmaster.google.com. 1 21600 3600 259200 300
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0