Mullvad VPN & NextDNS
I have setup Mullvad VPN on my router, and am using NextDNS as DNS server.
I’m still very new to this, so sorry if it’s a stupid question
Mullvad VPN tells me that I have a DNS leak, I ran a test and all it showed me was the NextDNS server. Is this a problem, can it be used to track me?
Thanks for your time in advance
The reason it shows as DNS Leak is simply because its not using a Mullvad DNS they most likely whitelist their own DNS servers to show as not leaking. Can it be used to track you, I mean NextDNS itself is to stop tracking/ads so honestly speaking it should perform even better than the stock DNS that they have since the filters block many domains.
The only possible issue would be with streaming potentially as I've heard from some VPN services that the DNS is also needed to bypass some Anti VPN measures taken by some sites. So in terms of privacy, as long as you trust NextDNS the "leak" is just NextDNS processing domains so nothing to worry about.
Whenever this happens, check https://test.nextdns.io/ to be sure if NextDNS is enabled. if it is then it isn't leaking, but Mullvad warns you because it detects you aren't using their servers, and since most people don't know jackshit about DNS or edit it, it could be deemed a leak, because a third party DNS server is resolving your DNS (obviously this is by choice, but Mullvad does not know that so it warns you regardless)
As for tracking, having a unique DNS server *can* help in generating a unique fingerprint, which could be used to track you, so using Mullvad DNS would be more practical for blending in (With a VPN like Mullvad, you get lost in the mix, using NextDNS *could* be making you unique in that mix, so proceed with care, but you have to make a choice based on your threat model.)
To read more about threat models: https://www.privacyguides.org/threat-modeling/