ns1.bt.es has no NS records.
NS records for this zone are defined at bt.es.
NS records for this zone are defined at bt.es.
Question and response
Question
dig ns1.bt.es. NS
Answer
The response has no answer records.
Authority
bt.es. 600 SOA ns1.bticglobal.net. hostmaster.eu.bt.net. 2021050635 3600 1800 1814400 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0