ns4.hkt.com has no MX records.
Question and response
Question
dig ns4.hkt.com. MX
Answer
The response has no answer records.
Authority
hkt.com. 1800 SOA ns3.hkt.com. dnsadmin.imsbiz.com. 2026021201 3600 900 86400 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0