mail2.oss.ntt.eu has no NS records.
NS records for this zone are defined at oss.ntt.eu.
NS records for this zone are defined at oss.ntt.eu.
Question and response
Question
dig mail2.oss.ntt.eu. NS
Answer
The response has no answer records.
Authority
oss.ntt.eu. 300 SOA ns1-06.azure-dns.com. azuredns-hostmaster.microsoft.com. 1 3600 300 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0