Should I change my DNS server?
The one free change that can filter adult content for a whole household, block a category of scam sites, and keep working when your provider's own service does not. What it does, what it cannot do, and the honest limits.
- Difficulty
- intermediate
- Time
- 30 min
- Read
- 6 min
Short answer
DNS turns a website name into an address, and by default your broadband provider does it. Changing it on the router applies to every device in the house at once and is worth doing for two specific reasons: family filtering, and blocking known malicious sites before your browser ever reaches them. It will not increase your broadband speed, it will not hide your browsing from your provider on its own, and if you get it wrong, nothing loads until you set it back.
Every time a device asks for a website, it first asks a directory service — DNS — to convert the name into a numeric address. Your router hands out your provider's directory service by default, and for most households it works invisibly and adequately. It is worth changing for reasons that have nothing to do with speed. A filtering DNS service can refuse to answer for adult content, gambling, or known malware and phishing sites, for every device in the house including ones with no parental controls of their own, without installing anything. That is a genuinely useful lever, and it is free. It is also the most over-claimed change in home networking, so this guide is as much about what it does not do.
Step by step
- Understand what DNS actually does before changing it.It is a lookup: name in, address out. It happens before any connection is made, which is why refusing to answer is an effective way to block something. It is not a filter on the traffic itself and it sees only the names requested, not the content.
- Decide which of the three reasons applies to you.Filtering — you want adult content or gambling blocked household-wide. Safety — you want known phishing and malware domains refused. Reliability or privacy — your provider's resolver is slow, or you would rather it were not your provider doing the lookups. If none of these apply, there is no need to change anything.
- Choose a provider deliberately, because you are giving them your browsing names.Whoever answers your lookups sees every domain your household asks for. That is a meaningful amount of information, and it moves from your broadband provider to whoever you pick. Read the chosen service's logging and retention policy — the major free ones publish theirs, and the family-filtering variants differ from the plain ones.
- Change it on the router, not on each device.One change in the router's settings covers every device including televisions, smart speakers and games consoles that have no DNS setting of their own. Log into the router — the catalogue has a guide on that — and look for DNS under internet or WAN settings. Write down the existing values before you change them.
- Write down what it was, and know how to undo it.Setting it back to automatic restores your provider's servers. If you make a mistake and nothing resolves, this is the recovery, and it is much easier if you noted the original setting first.
- Test it deliberately.Load a few sites, then test the thing you changed it for — a filtering service should visibly refuse an adult domain, and most publish a test page. Check the awkward cases too: a games console, a smart TV and any work laptop.
- Know which devices will ignore you.Some devices hard-code their own DNS regardless of what the router says — certain streaming devices and smart speakers do this. Modern browsers also increasingly use encrypted DNS to their own chosen provider by default, which bypasses your router's setting entirely unless it is turned off in the browser. This is the main practical limit on household filtering.
- Be realistic about what it protects against.It blocks known bad domains and categories. It does not stop a scam link on a site that is not on any list, it does not stop a message-based scam, and it does not filter content within a site. It is one useful layer, not a substitute for the conversation about what a household does online.
Common mistakes
- Expecting it to make the internet faster — It changes the lookup step, which is milliseconds. Every claim that changing DNS speeds up broadband is measuring something else, and it is the most common reason people change it for no benefit.
- Thinking it hides browsing from your provider — Your provider still carries every connection and can see which addresses you connect to, and the site names travel in the connection setup in many cases. Encrypted DNS to a third party changes who sees the lookups, not who carries the traffic.
- Changing it without writing down the original — If something breaks a week later, you want to be able to put it back exactly. Automatic is usually the right restore value, but knowing what it was avoids doubt.
If it doesn't work
Nothing loads after changing it
Cause: A typed address is wrong, or the service is unreachable — Fix: Set the router back to automatic. Every character of the address matters and there is no forgiving of a typo. Test with the values entered on one device first if you want a safer trial.
One site that should work is blocked
Cause: Category filtering is over-broad — Fix: Most filtering services have a way to allow a specific domain, either through an account or by choosing a less aggressive filtering tier. There is always a trade-off between coverage and false positives.
Filtering works on some devices and not others
Cause: The device is using its own DNS — Fix: Check the browser's secure DNS setting and turn it off, and check the device for a hard-coded DNS. Some routers can block outbound requests to other DNS services, which forces everything back through yours.
Speed is no different
Cause: It was never going to be — Fix: DNS affects the fraction of a second before a connection starts, not the speed of the connection. Any perceived improvement is in how quickly a page begins, on a provider resolver that was genuinely slow.
Your provider's parental controls stopped working
Cause: They were implemented in the provider's DNS — Fix: Many UK providers' filtering is DNS-based, so changing DNS turns it off. If you relied on it, replace it deliberately with the filtering tier of your new service rather than leaving a gap.
A work VPN stops resolving internal addresses
Cause: The VPN needs its own DNS for internal names — Fix: Expected, and usually handled by the VPN client automatically. If not, this is a reason to leave the work laptop configured for automatic DNS rather than forcing it.
Questions people ask
Is it safe to use a free public DNS service?
The major ones run by large infrastructure providers are reliable and publish their privacy policies, and they are used at enormous scale. The thing to be deliberate about is that you are choosing who sees your household's lookups. A small, unknown free service is a different proposition from a well-documented one, and there is no reason to use an obscure one.
What is encrypted DNS, and should I use it?
It encrypts the lookup so the network you are on cannot read or alter it — useful on public wifi, where it stops the network operator seeing what you look up. Browsers turn it on by default in many cases. Its side effect at home is that it bypasses your router's DNS setting, and therefore your household filtering, which is why the two need thinking about together.
Will this block adverts?
Some services block advert and tracking domains, and it works reasonably well across every device, including ones that cannot run an ad blocker. It is coarser than a browser extension — it blocks whole domains and cannot remove an advert served from the same domain as the content — and it occasionally breaks a page.
Can I run my own?
Yes, and self-hosted network filtering on a small always-on computer is a well-established hobbyist setup with genuinely good filtering. It also becomes a thing that has to keep working for the whole household to have internet, and that is the trade to think about before starting.