Not really DNS. They're actually checking the entire URL. They also check page content and other metadata.
If you're having distinct dns blocking errors, that's not Apple or it's a profile that's been set on your device.
The error screen I get says "Website not allowed" "'$domain' is a restricted website." - and it's coming from iOS/webkit itself, my network is unfiltered.
The error screen I get says "Website not allowed" "'$domain' is a restricted website." - and it's coming from iOS/webkit itself, my network is unfiltered.