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Network Isolation

Isolated networks restrict communication between network segments to protect sensitive resources from unauthorized access. This concept covers how and why network isolation is applied across backend servers, guest networks, and individual devices.

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About this video

Network isolation is a deliberate segmentation approach used to restrict communication between parts of a network, limiting exposure to threats and reducing the risk of unauthorized access to sensitive systems. Unlike general network segmentation, isolation specifically focuses on removing or tightly controlling connectivity rather than simply organizing traffic into separate zones. The practical result is that compromising one segment does not automatically grant access to another, which is a core principle in defense-in-depth security architecture. A common use case involves backend database servers that store sensitive information but have no need for direct internet connectivity or broad internal access. Placing these servers on an isolated network segment means they can only communicate with a defined set of application or web servers, and nothing else. An attacker who gains a foothold elsewhere on the network would face an additional barrier before reaching that data, as there is no direct path to the isolated segment. Isolation is also applied at the guest network level, where a separate segment provides internet access to visitors or untrusted devices while keeping those devices completely separated from internal infrastructure. This prevents lateral movement between the guest environment and more sensitive areas of the network. The concept can be extended further to prevent individual devices on the same guest network from communicating with each other, ensuring that one compromised device cannot be used to target another user on the same segment.

What you'll learn

What's covered

Isolated Networks

Key terms

Network Segmentation
The practice of dividing a network into smaller segments to improve performance and limit the spread of security threats.
Attack Surface
The total set of points in a system where an unauthorized user can attempt to enter or extract data.
Demilitarized Zone
DMZ
A network segment that sits between a trusted internal network and an untrusted external network, hosting public-facing services.
Virtual LAN
VLAN
A logical grouping of network devices that behave as if they are on the same network regardless of physical location.
Firewall
A network security device that monitors and controls incoming and outgoing traffic based on predefined security rules.
Network Isolation
The practice of separating a network segment so it has no direct connectivity to other networks or the internet, preventing unauthorized access to sensitive resources.

Topics

Network Isolation Network Segmentation Attack Surface Reduction Access Control Network Security Networking

Transcript

When we're separating out our different segmentations, sometimes we want an isolated network. But what is an isolated network?

What Isolation Means

This term isolate just means alone, or apart. Think of when COVID hit: we were isolated from other people, we separated ourselves out so we wouldn't pass on this virus. That is isolation. There are times when we want strict isolation within our networks as well.

Let me just give you an example of this. If you have a computer that you want to browse the internet on, then we don't want it isolated — we want it connected to the rest of the world. If we have web services that we want people to be able to access, we want it connected to the rest of the world.

But in this diagram right here, we have a database server on the back end. What is the need for people to have access to this database server? There really isn't a big need for it. Besides getting updates, there's not a big reason for these servers to get to the outside world as well.

So right here on the back end, what we might do is create an isolated network: a network that is not connected to the internet, but instead is just between these two devices right here. That way this bank of servers can talk to these database servers back and forth, and there is no other communication that can happen.

What this does is it isolates these database servers from being compromised at all. There could be sensitive information here, and if no one has direct access to them, then it makes it much more difficult for people to be able to grab information or steal information from them. They would have to somehow go through these servers right here. So we isolate those servers.

Examples of Isolation

There are several good examples here of isolation. For instance, we have a web server right here that needs to be accessed from the outside world, but we have that database server that's isolated on the back end. There's still a network connecting these two; it's just an isolated network that doesn't connect to the outside world.

We also have this isolated network right here. This isolated network is our guest network, and it has access to the outside world — machines on this network can still get to the outside world. It's just isolated from the rest of our more sensitive servers here. So we would say that that would be isolated.

Then here we have machines that are connecting into our guest network. In a lot of cases we don't really necessarily want one guest machine to compromise or take advantage of another guest machine. So what we could possibly do is create this isolation between the machines on our guest network, so at least they can't communicate through our equipment, through our access points.

So these would all be examples of isolation.

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