ts1-ext.sct.de has no CNAME records.
Question and response
Question
dig ts1-ext.sct.de. NS
Answer
The response has no answer records.
Authority
sct.de. 10800 SOA ts1.sct.de. st.sct.de. 2026022700 14400 3600 2419200 28800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0