toc.ntp.telstra.net has no MX records.
Question and response
Question
dig toc.ntp.telstra.net. MX
Answer
The response has no answer records.
Authority
ntp.telstra.net. 6400 SOA dns0.telstra.net. hostmaster.telstra.net. 2021030341 10800 3600 604800 6400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0