Sometimes the default DNS servers for ISPs in the Philippines don't work. Sometimes they get overloaded, sometimes they block certain sites and not others due to internal agendas (PLDT blocking Globe sites for eg.). So here's a list of the alternatives.
Outside the Philippines
Cloudflare, APNIC
1.1.1.1
1.0.0.1
2606:4700:4700::1111
2606:4700:4700::1001
[added Mar 2019. Current favourite]
Google DNS
8.8.8.8
8.8.4.4
2001:4860:4860::8888 (IPv6)
2001:4860:4860::8844 (IPv6)
OpenDNS (includes protection against malware)
208.67.222.222
208.67.220.220
Norton DNS
198.153.192.50
198.153.194.50
Inside the Philippines
Globe Telecom
202.52.163.6
202.52.163.7
202.52.162.39 (ns1.globeidc.com.ph)
202.52.162.40 (ns1.globeidc.com.ph)
202.52.167.70
202.52.167.71
203.127.225.10 (g-net.globe.com.ph)
203.127.225.11 (g-net1.globe.com.ph)
PLDT
210.14.4.37
112.206.232.66
119.92.150.133
122.52.136.140
119.92.233.159
58.69.254.3/58.69.254.8
Smart Bro
121.1.3.81
202.57.96.3
Sky Cable
202.78.64.83
202.78.64.84