ia-mailgw.APNIC.NET has no CNAME records.
Question and response
Question
dig ia-mailgw.APNIC.NET. NS
Answer
The response has no answer records.
Authority
apnic.net. 3119 SOA ns.apnic.net. dns-ops.apnic.net. 2020123480 3600 1800 691200 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0