DNS Privacy question

I’m going through Go Incognito again to try to apply some things I skipped a few years ago.
One is switching my internet connection to use a privacy respecting DNS.
Henry isn’t specific about recommending a particular DNS but if I squint I can see
https://dns.quad9.net/dns-query
in the Custom provider box.
Is that just a filler for demonstration sake, or the correct text to enter in the box?
I’m asking because when I look on Quad9’s how-to page it says to simply enter 9.9.9.9 in this box.

Also, I came across info on Mullvad’s DNS service
https://adblock.doh.mullvad.net/dns-query
and I know the company is highly respected in the privacy/security community.

Any recommendations of one over the other?

Also, should I be changing the DNS in Firefox settings or Window settings? The Mullvad tutorial says do it in Firefox settings, and the Quad9 tutorial says to do it in Windows settings.

That is indeed the correct text.
There’s also:

IPv4:
9.9.9.9
149.112.112.112
IPv6:
2620:fe::fe
2620:fe::9

I’ve never used Mullvad’s but I can vouch for Quad 9,.

As far as my knowledge you should change it in the windows settings for all of the device’s queries to go through.

So either
https://dns.quad9.net/dns-query
or
9.9.9.9
should work?

(answered my own question—9.9.9.9 did not work when I checked on.quad9.net but https://dns.quad9.net/dns-query did work)

Anyone tried Mullvad dns?

Yes the link is for you to put in the box whereas the addresses are added in the DNS settings of the network you’re connected to

I would advise not using the standard IPv4/IPv6 setup, unless that’s your only option. That kind of DNS is unencrypted, and not private. I would encourage you to use DNS-over-TLS (DoT). There is also DNS-over-HTTPS (DoH) option, but that’s also got some privacy/security problems. I can see quite a few users using it though, considering it was made by Google, and Windows has it natively.

To use DoT, on Windows you’d need to use a 3rd party tool, like Simple-DNScrypt (FOSS), YogaDNS (proprietary, but one of the easiest tools to use), or Portmaster (FOSS). If you’re a Linux user, it gets a bit more complicated with either distro specific tools, or editing text config files. Though, Portmaster is available on most distros.

Now, as for Mullvad’s DNS. If you trust their VPN, I think it’s also safe to trust their DNS servers. They’re privacy respecting, and a good option. Also, they’re the only option that I’m aware of that’s been audited. Whatever your option, I think either is a safe bet. I know other VPN companies use Quad9 for their DNS needs, including Proton.

NextDNS is a pretty nice service, kind of a pihole in the cloud for anyone. The free tier should meet most of everyone’s needs. They offer encrypted DNS as well.