mx1.isis-com.hu has no CNAME records.
Question and response
Question
dig mx1.isis-com.hu. NS
Answer
The response has no answer records.
Authority
isis-com.hu. 2401 SOA ns.isis-com.hu. hostmaster.isis-com.hu. 2026021201 86400 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0