DNS Firewall – Everything You Need to Know About It

With the increasing demands on security, networking, and IT teams, tools that do not cost much and reduce workloads are something that you look for.

DNS Firewall is one such piece of equipment. People who have no idea about what a DNS Firewall is and how it works continue to read this blog.

Introduction to DNS Firewall

In basic terms, DNS Firewalls work like traditional firewalls, where it redirects or blocks end-users from opening malicious sites.

When it comes to the difference, DNS Firewall can be applied to a different phase and layer; explicitly, data feeds like threat intelligence, which is applied to the DNS (Domain Name System).

It circumvents the visibility loss that makes the traditional firewalls a bit less effective because of the momentous increases in end-to-end encrypted traffic.

By the way, for people curious about the importance of a firewall, just read more.

Why Should Users Choose DNS Firewall?

DNS Firewall protects users against malware installation, data exfiltration, and identity theft.

Additionally, there are lots of other reasons for using this kind of Firewall as a unit of your security at multiple layers. Some important features of a DNS Firewall include the following:

Educate the End-users

If you attempt to link to a bad domain, then one can enlighten the end-user regarding the danger he has just avoided. For instance, potentially connecting to a phishing website.

It can either be carried out through a landing page that the end-user is redirected to or by contacting him directly. Thus, you turn a worse decision into a positive teaching occasion.

Free Up the Busy Team

By using this type of Firewall, you mitigate some serious problems automatically, which could arise on the network when it is being compromised. So, it provides the team with some free time for focusing on other pressing security and network issues.

Gain Insight to Be Practical

DNS Firewall offers more visibility to conceded clients or users on the network. It enables users to take some immediate actions with no time lags, which are either being warned by third parties or discovering the problem at a later date after the outbreak, which could be days, weeks, or months.

It is Simple to Apply and Easy to Maintain

After the application of this Firewall to the DNS, all clients on the network, such as IoT devices, get protected against accessing malicious websites. It also lessens deployment resources.

At the same time, the DNS Firewall continuously updates the data feeds against which latent connections are examined. Thus, it removes the requirement for updates and upgrades.

Brand Protection

For big brands, online security breaches could have a big impact on their business. To understand such consequences, you can look at the momentous data breach that happened with British Airways in the United Kingdom.

So, it is significant to have multi-layer security for keeping the users and company networks completely safe.

Low Cyber Risk Insurance Costs

Probably, insurance and other associated costs do not come under the budget and responsibilities of your department.

However, it is most likely that people in your company will be pleased to know that executing the DNS Firewall could reduce the cyber risk insurance amounts significantly and effectively.

How to Implement DNS Firewall?

Generally, there are three methods for implementing DNS Firewall. It is great to point out that all of these methods employ ‘threat intelligence data feeds’ for identifying bad domains. However, these methods differ in how users can utilize or access the feeds.

On-premises Open Source Software

Here, threat intelligence data feeds are moved through IXFR/AXFR to the DNS resolver in the form of zone files. Initially, DNS Firewall was designed to be a translatable and open standard, whereas its former home was BIND.

Now, various other DNS servers like Unbound, Knot, and PowerDNS offer support for employing DNS Firewall threat feeds.

On-premises Appliance

An internal application or solution that is located within the network works as a management system for the security infrastructure of your DNS.

It makes use of threat intelligence data feeds. As per the supplier, users enjoy the flexibility to select the preferred data feed supplier.


A service provider has its own DNS resolver secured by the DNS Firewall featuring threat intelligence data feeds and accessed by customers like managed services.

How Does DNS Firewall Work?

Now, it is time to know how this Firewall actually works. So, let’s have a look below!

DNS Firewall

Normal DNS Resolvers

When the end-users attempt to visit a domain or website, the DNS resolver queries a root server. After this, a high-level domain server and then the site’s server complete the resolution of the end-users request. The request of the client for accessing the website takes place irrespective of whether the website is nasty or not.

DNS Resolvers with DNS Firewall

Throughout the resolution zone process that comprises threat intelligence, data sets are queried. The entreated domain is examined for potential risks of security against these data sets. If some match is found, then the request gets redirected or blocked.

Phishing site with no DNS Firewall
Phishing site with DNS Firewall NXDOMAIN enabled
Phishing Landing Page Example

When the DNS Firewall is enabled, the end-users who have attempted to access a phishing site that, has been prevented from accessing and consequently secured from the potential danger that it could lead to.

Furthermore, as the mitigation occurs at the DNS level, there’s no need for the user to install other programs or software on the workstation. Now, it is time you should consider other things while implementing DNS Firewall.

How Much Does DNS Firewall Cost?

Price is the key factor when thinking of buying new hardware or services. Consider if users have a capital budget or if they are looking for a solution that can fit into their operational budget, depending on the subscription.

On-Premises Appliance

Here, prices are lower as compared to the cloud service. This is because users uninstall something onto their network.

But look if you need to pay any additional charges for using ancillary services on the appliances.

On-Premises Open Source Software

The price remains the lowest within this category as users transfer threat intelligence feeds into their own DNS resolvers. Thus, they would not have to pay any hardware costs.

Cloud Service

When it comes to price, cloud service is the most expensive one per user. This is so because of the infrastructure costs of the provider, which is in addition to the price of distributing the threat intelligence within their network.

However, the setup of the cloud service is comparatively easy. Here, users lose control and flexibility because it is a service that you need to share with various users. Therefore, you even end up reimbursing for the data feeds that you actually do not require.

FAQs Regarding DNS Firewall

What Do You Mean by DNS Firewallthreat Feeds?

DNS Firewall Threat Feeds enable DNS resolvers to select particular actions to be carried out for a sum of domain name data’s collections (zones), which are usually delivered in the Response Policy Zone format. It also includes blocking, dropping, and passing through traffic.

Why Is There a Need to Restrict DNS Resolution?

On the internet, there are domains, IP addresses, and networks whose main objective is to cause damage or steal data from unsuspicious users who access their sites and servers.

For instance, a phishing website (a part of the threat feed) made the chief reason for stealing information that can be utilized for spam campaigns. These spam campaigns are sent to end-users on the network, requesting them to confirm their account.

The received emails are not blocked through spam filtering, and thus, the messages get delivered into the inbox of the user. When users tap on the link to verify their accounts, the system is not able to fix the phishing site. This action protects users from granting personal information.

Also, it potentially prevents the workstation from getting infected with botnet software. Restricting malicious content even provides you with the potential to educate the users immediately.

What Software and Hardware Are Required to Support Threat Feeds?

It is quite possible that the existing hardware that runs the DNS resolver could handle the processing of Threat Feeds in RPZ format.

Meanwhile, we recommend you some hardware configurations as follows:

  • 8 gigabytes of RAM
  • Eight core CPU
  • Bare-metal devoted server

When it comes to software, the latest BIND version should be installed. Please note that most of the apt-get, DNF, and yum repositories have out-of-date versions available. Thus, it is advisable that BIND updates should be directly downloaded from ISC.

What Do the DNS Resolvers Return if a Website Gets Blocked?

In many circumstances, DNS resolvers return an invalid domain (NXDOMAIN) response if something is comprised in a threat feed.

However, it is quite possible to point to internal IP resources, which enable the block to redirect to informational pages, which provide some education, warning, or give an insight into why that thing was blocked.

Do the Prices Change for Threat Feeds?

Usually, pricing depends on the user numbers and will be even adjusted accordingly. Nearly every two years, the price for this service may be modified in line with market value and inflation.

DNS Firewall features the capability to free up teams for accomplishing other tasks. It even assists in building a protected proactive network experience for all working within the organization.

Now, you have an idea of how the DNS Firewall works. So, install the DNS firewall and protect your system from malicious content.



10 years of experience in information and computer technology. Passionate about electronic devices, smartphones, computers, and modern technology.