mail.opticalfiber.ro has no CNAME records.
Question and response
Question
dig mail.opticalfiber.ro. NS
Answer
The response has no answer records.
Authority
opticalfiber.ro. 300 SOA ns.opticalfiber.ro. hostmaster.opticalfiber.ro. 2013100810 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0