mx.chrono24service.com has no NS records.
NS records for this zone are defined at chrono24service.com.
NS records for this zone are defined at chrono24service.com.
Question and response
Question
dig mx.chrono24service.com. NS
Answer
The response has no answer records.
Authority
chrono24service.com. 3600 SOA dns.chrono24service.com. hostmaster.chrono24service.com. 1296696819 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0