mail.pldt.net has no CNAME records.
Question and response
Question
dig mail.pldt.net. NS
Answer
The response has no answer records.
Authority
pldt.net. 10182 SOA ns1.pldt.net. root.ns1.pldt.net. 2014113592 3600 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0