mail-internal.superhosting.cz has no CNAME records.
Question and response
Question
dig mail-internal.superhosting.cz. NS
Answer
The response has no answer records.
Authority
superhosting.cz. 3600 SOA ns1.superhosting.cz. dns.superhosting.cz. 2026030604 3600 3600 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0