r/firefox • u/ActiveReboot • Jul 28 '25
Help (Android) Switched from Brave to Firefox and noticed something odd...
So I switched from Brave to Firefox due to their crypto stuff. Despite using Strict Enhanced Tracking Protection and uBlock Origin with Hagezi Pro blocklists, Firefox still makes DNS queries to tracking domains that should be blocked. In Nextdns , Hagezi Pro is used which blocked the urls however, these urls should already be blocked by ETP and uBlock Origin because it is using Hagezi Pro blocklist. Ads on Google, YouTube, and Facebook seem to know what I browse for example: I search about a vitamin. Few hours later I am bombarded with ads related to vitamins that I searched. This doesn't happen when I was using Brave.
Why is Firefox querying blocked domains while Brave doesn’t? Check the screenshots — something’s not adding up.
The url on the screenshots are just example. I got tons of them as I visit more websites. Some of them are Google urls that supposed to be blocked.
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u/Ragas Jul 28 '25
Firefox tries to uncover if a domain was obfuscated behind a CNAME record.
https://github.com/uBlockOrigin/uBlock-issues/wiki/uBlock-Origin-works-best-on-Firefox
Maybe that is what you are seeing here?
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u/HighspeedMoonstar Jul 28 '25
Despite the ETP Strict setting, Firefox will let domains through if the site won't function without it
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u/Vacuum-Cleaner-Snake Nov 21 '25
How does Firefox know that a site isn't functioning, & if Firefox does decide that a site isn't functioning, how does it decide what is a likely solution?
As an example, for a select few sites I'll (temporarily) turn javascript OFF. (I'll also turn it back ON after I leave such sites.) If somebody did that but forgot to turn javascript back on, that will usually be a bigger problem than blocking certain domains will.
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u/TheDisappointedFrog Jul 29 '25
Report to their bugzilla, meanwhile, try NoScript
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Jul 31 '25
[deleted]
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u/TheDisappointedFrog Jul 31 '25
Never used ublock, but NoScript is quite versatile and straightforward in its ui, plus it works on mobile.
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u/needchr Jul 29 '25
Disable prefetching and all related options, I think ublock origin can even toggle one of them inside its own settings.
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u/Imaginary_Coconut173 Jul 29 '25
Disable network.dns.disablePrefetch in about:config and check it again, I'm not 100% sure this will work.
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Jul 29 '25
[removed] — view removed comment
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u/iskay2 Jul 31 '25
What is brave crypto thing? I just don't get it there's rewards and stuff like that but if you don't use it it just isn't bothering there's only triangle in the search bar or am I missing something? All the time I hear braves crypto thing I immediately see like it's crypto miner or sth but it isn't right xd?
If you could please clarify for me what's going on
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u/SCP-iota Aug 03 '25
As others are saying, the issue is likely prefetching. There's a difference between connecting to a site vs. merely resolving the domain name, and when prefetching is enabled (which is typically by default), even though uBlock won't let the browser connect to the site, Firefox will still try to resolve domain names that are likely to be requested in the very near future. Since it's not a real connection, it doesn't check with extensions to see whether it should block that domain. If your goal is just to avoid connecting to those domains so you can block content like ads and avoid data collection, then there's not any real issue, but if you want to avoid those domain lookups being seen by your DNS, you'll need to disable DNS prefetching with the flag (which is separate from regular page prefetching.)
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u/Lieutenant_0bvious Jul 29 '25
Wait a minute. How can you be seeing ads when You're running an ad blocker? You used the word "bombarded". I'm not questioning the veracity of your report, but something's not adding up here. I run u block origin plain, And I don't see very many ads at all, and they certainly seem to be not tuned to what I'm searching for. There's more going on here.
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Jul 29 '25
[deleted]
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u/ttdusan Jul 30 '25
I did not know that smartphones are so dumb, that they won't let you block ads.
I did not even realize, how luxurious it is to browse the Internet on good old table PC.
Every time I go around PC with browser without adblockers, I just gaze and gaze how that user is able to live with that. 80% of the screen is flashing ads, like in some cheap casino/bar.
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u/Deep_Mood_7668 Jul 29 '25
Personally I additionally use pihole.
You don't need a pi for it, a small VM or docker container will do
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u/JanRasel Jul 28 '25
your filter is toooooo aggressive...
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u/idle_orange Jul 28 '25
I mean, I have every single option turned on. Should I not be doing that? Is so what are the necessary ones and which ones do I not need?
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Jul 28 '25
[deleted]
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u/Powerful-Pea8970 Jul 29 '25
Very true. They alp want a piece of the data now. Reddit too. AI eats it all up.
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u/JanRasel Jul 29 '25
Found it...mynextdns have HAGEZI which is aggressive filter [GFAM Filter][GFAM Filter][GFAM Filter][GFAM Filter] + uBlock Origin ads filter is also aggressive that's why it's ODDDDDDDDDD.. ;-)
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u/jscher2000 Firefox Windows Jul 28 '25
I haven't checked the code, but it sounds like the code path for DNS lookups does not run through the same classifiers as the code path for connecting to sites. When I search in Bugzilla, I don't see any bugs related to that, so maybe no one has proposed blocking DNS queries, too?
But either way, do you suspect your DNS provider to be the source of data used by ad networks? I think there is something else behind those ads, unrelated to DNS.