ns.net.ua has no MX records.
Question and response
Question
dig ns.net.ua. MX
Answer
The response has no answer records.
Authority
net.ua. 1800 SOA ho1.net.ua. info.eunic.net.ua. 2602221925 3600 1800 1814400 1800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0