r01es.mail.s-web.de has no NS records.
NS records for this zone are defined at s-web.de.
NS records for this zone are defined at s-web.de.
Question and response
Question
dig r01es.mail.s-web.de. NS
Answer
The response has no answer records.
Authority
s-web.de. 1800 SOA ns1.s-fg-net.de. domreg.f-i.de. 1552 10800 3600 2419200 1800
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0