mailex0.world4you.com has no NS records.
NS records for this zone are defined at world4you.com.
NS records for this zone are defined at world4you.com.
Question and response
Question
dig mailex0.world4you.com. NS
Answer
The response has no answer records.
Authority
world4you.com. 3600 SOA ns-ionos.ui-dns.com. dnsadmin.ionos.com. 2025042090 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0