DNS löst plötzlich keine manuell angelegten lokalen Hostnamen mehr auf

Externe Domain:

❯ dig @10.16.1.1 www.schuldomain.de

; <<>> DiG 9.11.3-1ubuntu1.16-Ubuntu <<>> @10.16.1.1 www.schuldomain.de
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49385
;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 2, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;www.schuldomain.de. IN A

;; ANSWER SECTION:
www.schuldomain.de. 900 IN CNAME webXX.belwue.de.
webXX.belwue.de. 300 IN A 129.143.XXX.XX

;; AUTHORITY SECTION:
schuldomain.de. 3600 IN SOA server.schuldomain.de. hostmaster.schuldomain.de. 970 900 600 86400 3600

;; Query time: 401 msec
;; SERVER: 10.16.1.1#53(10.16.1.1)
;; WHEN: Mon Dec 20 15:43:13 CET 2021
;; MSG SIZE rcvd: 126

Interne domain

❯ dig @10.16.1.1 start.schuldomain.de

; <<>> DiG 9.11.3-1ubuntu1.16-Ubuntu <<>> @10.16.1.1 start.schuldomain.de
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 47758
;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;start.schuldomain.de. IN A

;; Query time: 1 msec
;; SERVER: 10.16.1.1#53(10.16.1.1)
;; WHEN: Mon Dec 20 15:43:37 CET 2021
;; MSG SIZE rcvd: 31

Seltsam oder?