Active Defences – Protective DNS


The NCSC provide a range of services for public organisations (such as the NHS). Part of these include active defence services. One of these is protective DNS!

Protective DNS

Protective DNS acts as a sink holing mechanism to help prevent an unsuspecting web user from visiting a malicious site (such as a phishing site or one hosting malware). Well what’s that?

So DNS acts as an address book, you enter a URL e.g. and your device does a look up to its name server, if the address exists it will return back a valid response. Now protective DNS is where rather than forwarding your requests to raw internet DNS servers, we use a managed service which has a constantly updated list of known malicious sites, etc. That way, if you try and visit a bad site, you get given a safe address and your device doesn’t even get there! Now my explanation here is really simple, it’s a bit more complex in reality. Luckily the team at NCSC have written up a far more in depth view of this.

If you are a public organisation hopefully you’ve already got this and a load of other controls deployed, however I wanted to highlight this again, as if you are a public sector organisation you can request and leverage this as one of the ways to help prevent the impact of phishing and typos, etc. (I typo all the time!)

For those of you who are operating at a personal or business level, there are a range of commercial and free services available such as:

Another line of defence

So, no matter how big or small your organisation is, and if it is public or private you can implement protective DNS as one of the many controls required to keep you safe from cybercriminals. Remember, you need a layered approach to cyber security and protective DNS is just one of those that can be a great way to fight back!