secure.mail.provider.nl has no NS records.
NS records for this zone are defined at provider.nl.
NS records for this zone are defined at provider.nl.
Question and response
Question
dig secure.mail.provider.nl. NS
Answer
The response has no answer records.
Authority
provider.nl. 86400 SOA dns.resolver.domains. hostmaster.provider.nl. 2025112701 86400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0