mail01.vc-cc.de has no CNAME records.
Question and response
Question
dig mail01.vc-cc.de. NS
Answer
The response has no answer records.
Authority
vc-cc.de. 2259 SOA ns01.vcvn.de. hostmaster.vc-cc.de. 1765455276 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0