Disclaimer: While I try to remain as unbiased and objective as possible in this blog post, I have stated my preference for Mullvad's DNS, however please do not use my recommendation as a glowing review. I recommend you do your own research and come to conclusions, or you can take my word for it.
Did you know that even if you use the most secure browser and Operating System in the world you could still potentially be giving all of your network traffic to Google and/or your ISP?
This happens because of your Domain Name System (Which is often referred to as simply your DNS.) To put it simply, the DNS takes a URL you give it and converts it to an IP Address, instead of memorizing 172.67.183.128 to visit Gluo, you can simply just remember gluo.xyz. It's a handy system!
An additional benefit of a third-party DNS is they offer more control. If you don't want to see any advertisements online, you can use a DNS that blocks all requests to known advertisement providers websites.
However, these DNS servers are often fairly untrustworthy. They're typically hosted by large companies like Google who might be logging all of your network requests. For DNS settings there are three DNS servers to worry about, your browsers DNS, your Operating Systems DNS, and your Routers DNS. These can be set separately and can route traffic differently based on what you're doing on your computer/around your house.
To quickly explain what gets affected by your DNS settings at different levels, it's quite simple. Anything you do in your browser will be fed through the browser set DNS, anything else on your OS (like an installed program that doesn't let you pick the DNS) will be fed through your Operating Systems DNS. It's good practice to set your browser and OS DNS to the same thing, it can stop some weird behaviour.
As for the routers DNS that's where it gets a bit weird. Your router has a predefined DNS that it'll tell devices to use, it's just a “trust me bro” claim from the router. Your devices will typically just use the DNS without question. The DNS provided by the router tends to be either Googles DNS or your ISPs DNS which is often based on Googles DNS anyway. The modification of the routers DNS will simply change the DNS for the devices that wont let you configure the DNS settings on them (unless they're programmed to always use a different DNS)
Before we talk about changing your DNS, you should learn about some more trustworthy DNS providers. These include Mullvad, Quad9, and Cloudflare.
You are also able to prevent your ISP seeing what websites you visit with the shown DNS providers! All the providers shown here use DNS over HTTPS, which in simple terms just hides what websites you're connecting to from your ISP.
Mullvad by far offers the most control when it comes to what you see on the internet and what doesn't get shown to you. They are extremely trusted in the online privacy community and is my personal pick.
Similarly to Mullvad, Quad9 is a highly trusted DNS provider, however they don't offer as many DNS blocking options. They offer three options, however there's only one that matters for privacy:
Cloudflare, another well trusted company (However not really known for their Privacy side, so take this with a pinch of salt) offers their own DNS. Theirs is unique in that they have backup DNS servers with different IP address' just in case their primary one goes down!
Changing your DNS can be annoying, one service might only accept the DNS IP Address, and another might only accept the DNS URL, while some might accept both. Some might require you to remove https:// from the start and/or remove /dns-query from the end. It's a stupid, non-standardized system, especially with the new DNS-over-HTTPS system. It might take a few tries but with some testing you'll get it to work! Always read any and all provided guides when it comes to DNS settings so you can do less tinkering.
Another annoyance is that changing your DNS system varies so much from Operating System to Operating System that I cannot provide meaningful guides without a solid 10 pages steps. To change the DNS system on your Operating System I recommend you do your own research, there are a lot of great Operating-System specific guides out there.
Luckily when it comes down to browsers, it is a lot easier.
If you use Firefox, LibreWolf, Waterfox, or any other Firefox based browser, then follow these steps:
If you use any Chromium based browsers the steps may be slightly different depending on your browser, however the following guide was made using ungoogled Chromium.
Changing your DNS on mobile is (typically) supported but, again, it varies from platform to platform. iOS is very annoying about it but it's still possible. As for Android, where exactly you can change it will vary from manufacturer to manufacturer, so for your mobile device too, you will need to do some research.
An easy way to test where your DNS queries are going to is by using iVPN's DNS leak test over at https://www.dnsleaktest.com, just click “Extended Test” and it will tell you what DNS servers you're using, it may take a minute or two though, be patient! The only downside to this test is that it will tell you what your browser communicates with, this doesn't necessarily tell you what your OS will communicate with.
Lastly, when it comes to your networks DNS I can provide no guides on how to change that either. It will vary from router to router. Any guide I give will almost certainly be useless to you. You will need to go online and find resources regarding your specific router.
That's all you need to know about changing your DNS settings! Remember, just changing your DNS won't give you complete privacy online, nothing will. However it's a lot better than just willingly passing all of your network traffic through Googles servers.