What Is DNS Filtering and Why Does Your Melbourne Business Need It?
- Lance Djordjevic
- 2 days ago
- 9 min read
Every time an employee opens a website, follows a link in an email or signs in to a cloud service, their device needs to find the correct destination on the internet.
Most of the time, this happens safely in the background. However, the same process can also direct users towards phishing pages, malicious downloads and websites designed to steal business credentials.
DNS filtering adds a security checkpoint before that connection is made. It can prevent a device from reaching a known malicious or restricted domain, helping stop a risky click from becoming a much larger cyber security incident.
For Melbourne businesses, DNS filtering is a practical extra layer of protection for office computers, laptops and remote workers. As part of our Managed IT Services and Cyber Security Services, BITS Melbourne combines DNS filtering with endpoint protection, email security, multi-factor authentication, password management, backups and proactive monitoring.
First, What Is DNS?
DNS stands for Domain Name System. It works a little like a contact list for the internet.
People remember website names such as bitsmelbourne.com.au, but computers connect using numerical IP addresses. When you enter a website address, your device sends a DNS request to find the address of the server it needs to contact.
Without DNS, staff would need to remember a long string of numbers for every website and online service they use.
This lookup usually takes place in a fraction of a second, which is why most people never notice it happening.
What Is DNS Filtering?
DNS filtering applies security and business rules to that lookup process.
Before a website address is translated into an IP address, a secure DNS service checks the requested domain against threat intelligence, security categories and your organisation's policies.
If the domain is considered safe and permitted, the request continues normally. If it is known to host phishing, malware or other restricted content, the connection can be blocked before the website loads.
The Australian Signals Directorate notes that a protective DNS service can be an effective way to block requests to known malicious domains. Its network security guidance also explains that DNS event logs can help investigate attempted or successful network compromises.
DNS filtering is sometimes described as protective DNS, DNS security or DNS content filtering. Although the exact features vary between platforms, the main purpose is the same: prevent devices from connecting to destinations that present an unnecessary risk.
How Does DNS Filtering Work?
The process can be broken into four simple steps:
A user or application requests a domain. An employee clicks a link, opens a website or an application attempts to connect to an online service.
The DNS service checks the destination. The domain is compared with current threat intelligence and the policies configured for the business.
The request is allowed or blocked. Safe destinations continue to load. Known malicious or restricted domains are blocked before a normal connection is established.
The activity is recorded. Business-grade platforms can log blocked requests, helping identify risky behaviour, infected devices or repeated attempts to contact suspicious infrastructure.
For staff, the experience is usually simple. Safe websites continue working as normal, while blocked destinations display a warning or fail to connect.
What Threats Can DNS Filtering Help Block?
The protection available depends on the DNS filtering service and how it is configured.
A properly managed business solution can help reduce exposure to several common threats.
Phishing and Fake Login Pages
Phishing websites are designed to look like trusted services such as Microsoft 365, a bank, a courier portal or an accounting platform.
If an employee clicks a phishing link and the destination has been identified as malicious, DNS filtering can block the website before the employee enters a username, password or payment information.
Malware and Dangerous Downloads
Some websites are built or compromised to distribute malicious software. Others use misleading download buttons, fake browser updates or fraudulent security warnings to convince users to install something harmful.
Blocking the domain before it loads reduces the opportunity for malware to reach the device.
Ransomware and Command-and-Control Traffic
Malware already present on a computer may attempt to contact an external server for instructions, additional payloads or data transfer. Protective DNS may help interrupt that communication when the destination is known to be malicious.
This is valuable because DNS filtering can protect against both the initial risky click and some activity that occurs after a device has been compromised.
Suspicious or Newly Identified Domains
Quality DNS security platforms continuously update their threat intelligence as new malicious infrastructure is discovered. Depending on the platform, policies can also be used to restrict newly registered, suspicious or poorly categorised domains while they are assessed.
Unwanted Website Categories
DNS filtering can also support an organisation's acceptable-use policies. Businesses may choose to restrict categories such as adult content, illegal downloads, gambling, anonymisers or other websites that create security, legal or productivity concerns.
These policies should be based on a genuine business requirement rather than blocking sites without a clear reason.
A Simple Example: The Fake Microsoft 365 Document
Imagine an employee receives an email claiming that a supplier has shared a Microsoft 365 document.
The message looks convincing, and the employee clicks the link. Instead of opening Microsoft 365, it points to a fake sign-in page created to steal their password.
Email security should be the first opportunity to detect or remove the message. If the email still reaches the employee, DNS filtering provides another chance to block the destination when its domain has been identified as unsafe.
If the phishing site is very new or hosted through a service that is otherwise trusted, the DNS filter may not stop it. That is why Multi-Factor Authentication, a business password manager, endpoint protection and security monitoring remain essential.
This layered approach is also why the incident in our Business Email Compromise case study was detected and contained before it became a much larger problem.
Why DNS Filtering Matters for Melbourne Businesses
It Reduces the Impact of Human Error
Even well-trained employees can click a convincing link. DNS filtering adds a technical safety net that does not rely entirely on the user recognising every threat.
Security awareness training still matters, but staff should not be the only line of defence.
It Can Protect More Than Web Browsers
DNS requests are made by browsers, desktop applications, background services and other connected devices. Because filtering operates at the DNS layer, it may identify risky connections that are not created by someone manually opening a web page.
It Can Cover Remote and Hybrid Workers
Network-level filtering protects devices while they are connected to the configured office network. With the correct roaming or endpoint protection installed, business laptops can also remain protected when staff work from home, visit a customer or connect through another internet service.
This remote coverage needs to be deliberately configured. Simply changing the DNS settings on an office router will not automatically protect a laptop after it leaves the building.
It Improves Visibility
DNS security logs can show which malicious destinations were blocked, which device made the request and whether the same activity is recurring.
For example, repeated attempts to contact a suspicious domain could indicate an unwanted browser extension, an infected device or a user repeatedly opening a dangerous link. That information gives an IT provider a useful starting point for investigation.
It Supports Consistent Business Policies
Centralised policies make it easier to apply the same protection across different users, devices and locations. Allow lists and block lists can also be used to handle legitimate business exceptions without disabling the entire security control.
It Works Quietly in the Background
Once DNS filtering is correctly deployed, staff generally do not need to operate it or remember an extra security step. It becomes part of the normal internet connection and only becomes visible when a request is blocked.
DNS Filtering vs Other Cyber Security Tools
DNS filtering is useful because it acts early, but it does not replace the rest of your security stack.
Security layer | Primary role |
Email security | Detects malicious messages, attachments, impersonation and phishing before they reach an inbox. |
DNS filtering | Blocks connections to known malicious or restricted domains before the destination loads. |
Endpoint protection | Detects malicious files, processes and suspicious behaviour on the device. |
Firewall | Controls network traffic between devices, networks and the internet. |
Multi-factor authentication | Adds another identity check when someone attempts to sign in. |
Application allowlisting | Controls which applications and executable files are permitted to run. |
Backup and disaster recovery | Provides a recovery path if data is deleted, corrupted, encrypted or otherwise lost. |
Each tool covers a different part of the attack path. When several layers are managed together, an attack that gets past one control still has other barriers to overcome.
What DNS Filtering Cannot Do
DNS filtering is not a complete cyber security solution on its own.
It cannot:
Guarantee that every phishing website will be identified immediately
Repair weak or reused passwords
Inspect every email attachment or downloaded file
Replace endpoint protection or application control
Patch vulnerable software
Recover deleted or encrypted business data
Prevent every threat delivered through an otherwise trusted website
It may also be bypassed if browsers, VPN applications or unmanaged device settings are allowed to use a different DNS service. This is why changing one setting on the router is not the same as deploying and managing business-grade DNS protection.
Businesses still need strong identity security, reliable backups and properly maintained devices. Our guides to Microsoft 365 backup and business password management explain two of those additional layers in more detail.
What Should You Look for in a Business DNS Filtering Solution?
When comparing DNS filtering options, look beyond a basic list of blocked websites. A business-grade service should provide:
Frequently updated threat intelligence
Protection for devices both inside and outside the office
Centralised security and content policies
Clear reporting for users, devices and locations
Custom allow lists and block lists
Alerts or useful investigation data
Controls that reduce easy bypass methods
Reliable, low-latency DNS resolution
Ongoing policy review and technical support
The right configuration will depend on how your business operates. A warehouse with shared devices, a medical clinic with sensitive information and a professional office with remote workers may each require different policies.
How BITS Melbourne Helps Manage DNS Security
BITS Melbourne helps businesses implement DNS filtering as part of a broader, managed cyber security strategy.
We can:
Review how your current devices and networks resolve DNS requests
Configure protection for office networks and managed endpoints
Extend coverage to remote and hybrid workers where required
Create sensible security and acceptable-use policies
Test legitimate business websites and manage necessary exceptions
Review suspicious or repeated blocked requests
Maintain policies as devices, staff and business requirements change
Combine DNS filtering with email security, endpoint protection, application allowlisting, patching, Microsoft 365 protection and backups
This approach means DNS filtering is not simply switched on and forgotten. It forms part of the ongoing Business IT Support and security management protecting your wider environment.
Frequently Asked Questions About DNS Filtering
Does a Small Business Really Need DNS Filtering?
If your business relies on email, cloud applications, online banking, remote access or internet-connected devices, DNS filtering can provide a useful additional layer of protection. The appropriate setup should still reflect the size, risk profile and working arrangements of the business.
Will DNS Filtering Slow Down Our Internet?
A reputable and correctly configured service should add very little noticeable delay to normal browsing. DNS performance and reliability should still be considered when choosing a provider, particularly for businesses with several sites or latency-sensitive applications.
Does DNS Filtering Protect Employees Working from Home?
It can, provided protection is installed or enforced on the managed device. Office network settings alone generally stop applying when the employee connects through their home internet or another network.
Can DNS Filtering Accidentally Block a Legitimate Website?
Yes. False positives or overly restrictive categories can occasionally block a genuine business website. A managed service should make it straightforward to review the request and create a safe exception where appropriate.
Is DNS Filtering the Same as Antivirus?
No. DNS filtering aims to stop a device from reaching a risky domain, while antivirus or endpoint protection looks for malicious files and behaviour on the device. They are most effective when used together.
Is DNS Filtering Included with Microsoft 365?
Not automatically in every Microsoft 365 environment. Some Microsoft security products and licence combinations provide web or network protection features, but their availability and configuration vary. A proper assessment is needed to confirm what is licensed, enabled and protecting each device.
Stop Malicious Websites Before They Reach Your Team
DNS filtering is one of the quieter layers of business cyber security, but it can make a meaningful difference. By stopping access to known malicious destinations before they load, it reduces the opportunity for phishing, malware and other online threats to reach your staff and devices.
It works best as part of a layered strategy that also includes email security, endpoint protection, multi-factor authentication, password management, application control, patching, backups and ongoing monitoring.
If you are unsure whether your business has DNS filtering in place—or whether your laptops remain protected outside the office—book a Free IT Assessment with BITS Melbourne.
We will review your current IT environment, identify practical security gaps and explain which improvements would provide genuine value for your business.
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