Hi @PHB-Sales
Thanks for reaching out!
Looks like the name servers were changed:
dig phb-consulting.de NS +trace | tail -n 6
phb-consulting.de. 28800 IN NS ns2.domaindiscount24.net.
phb-consulting.de. 28800 IN NS ns1.domaindiscount24.net.
phb-consulting.de. 28800 IN NS ns3.domaindiscount24.net.
;; Received 1332 bytes from 2604:4500:c:3:66:206:3:125#53(ns2.domaindiscount24.net) in 87 ms
The last line, Received 1332 bytes, shows the name server that answered the above query is domaindiscount24.net and not a Netlify name server mentioned here.
Please check out this Support Guide on how to detect and fix an inactive DNS Zone.
Let us know if you have any questions.