I had been using the Lockdown app when not on VPN for my iPhone. Based on the block logs, it seems to work well for blocking tracking by non-Apple big tech companies (amazon, Facebook, google, etc). I manually added Apple tracking/Advertising domains to the custom block list and it worked somewhat but recently stopped working entirely. I figured Apple must have been bundling the Ad traffic with other ‘legitimate’ traffic or changed their domains. I had mostly given up on blocking ads within Apple Apps after adding many domains from other block lists intended to stop apple tracking/ads with no effect.
I had been running Quad9 DoH on my phone for some time but got interested in NextDNS due to its more advanced/custom features. I added the Apple Tracking block list to my configuration and tried it out. To my great surprise Apple Ads disappeared from the News app. I checked the logs to see what unknown domains Apple had hidden their ads in…
…the same domains I had manually added to the Lockdown App
My Analysis on what is going on:
Lockdown uses a ‘dummy’ VPN profile to run the traffic through and block domains on device. NextDNS uses the DoH capability native to iOS.
Three possibilities come to my mind based on this.
iOS leaking traffic outside a VPN for core services (a known issue) to keep their ad revenue going
Lockdown app intentionally ignoring the Apple Ads domains (lockdown is run by former Apple Employees)
Lockdown app custom domain feature is broken
To test this I turned on ProtonVPN with ad blocking. The ads went away. Thus the ads cannot be the result of VPN leakage. Thus it looks like Option 2 or 3 is likely. Unless anyone else has some idea of what might cause this?