ns3.ps.oktawave.com has no MX records.
Question and response
Question
dig ns3.ps.oktawave.com. MX
Answer
The response has no answer records.
Authority
ps.oktawave.com. 86400 SOA ns1.ps.oktawave.com. hostmaster.ps.oktawave.com. 2026021700 14400 3600 604800 86400
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0