ns2.world-net.net has no MX records.
Question and response
Question
dig ns2.world-net.net. MX
Answer
The response has no answer records.
Authority
world-net.net. 300 SOA ns1.world-net.net. hostmaster.world-net.net. 2025101601 3600 1800 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0