srv01.m-haditec.de has no CNAME records.
Question and response
Question
dig srv01.m-haditec.de. NS
Answer
The response has no answer records.
Authority
m-haditec.de. 9902 SOA ns1.m-haditec.de. h\.oezoguz.m-haditec.de. 1741102313 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0