Apex domains cannot have CNAME records.
Question and response
Question
dig com.ph. NS
Answer
com.ph. 5 NS ns2.cuhk.edu.hk.
com.ph. 5 NS ph.communitydns.net.
com.ph. 5 NS 1.ns.ph.
com.ph. 5 NS ns4.apnic.net.
Authority
The response has no authority records.
Additional
1.ns.ph. 49803 A 206.51.255.1
ns4.apnic.net. 5 A 202.12.31.53
1.ns.ph. 49803 AAAA 2620:171:805:ad2:7068:0:0:1
ns4.apnic.net. 5 AAAA 2001:dd8:12:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0