drezna.admin.sardinasystems.com has no CNAME records.
Question and response
Question
dig drezna.admin.sardinasystems.com. NS
Answer
The response has no answer records.
Authority
admin.sardinasystems.com. 60 SOA a.ns.admin.sardinasystems.com. hostmaster.admin.sardinasystems.com. 1772317738 300 60 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0