sms.staging.squalomail.com has no NS records.
NS records for this zone are defined at squalomail.com.
NS records for this zone are defined at squalomail.com.
Question and response
Question
dig sms.staging.squalomail.com. NS
Answer
The response has no answer records.
Authority
squalomail.com. 60 SOA ns1.itars.eu. hostmaster.itars.eu. 2025111800 60 60 604800 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0