Apex domains cannot have CNAME records.
Question and response
Question
dig pldt.net. NS
Answer
pldt.net. 4 NS ns2.pldt.net.
pldt.net. 4 NS ns1.pldt.net.
Authority
The response has no authority records.
Additional
ns1.pldt.net. 4 A 58.71.1.34
ns2.pldt.net. 4 A 58.71.2.4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0