You might want to switch to the "Policy 2" Norton DNS, OpenDNS Family Shield (now owned by Cisco, who also owns Sourcefire, one of the largest intrusion protection system companies), or the Comodo settings for the public-facing DNS on the RPi. You can modify the dnsmasq settings in /etc/dnsmasq.d/01-pihole.conf, then reload or restart dnsmasq.
The advantage of this choice is that it doesn't require updating of the text files because the entries are managed by the DNS provider.
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