Monitoring Networks With Subnets and VLANs

4 min

Guide to deploying Domotz to monitor networks with subnets and VLANs

In today’s interconnected world, the complexity of network infrastructures is continually increasing. As Managed Service Providers and IT professionals, we’re often faced with the challenge of ensuring optimal performance and security across networks that span multiple subnets and VLANs. Understanding the intricacies of these networks is crucial for effective monitoring and management. 

This article delves into the essentials of deploying Domotz for comprehensive network monitoring across various configurations, from simple single subnet setups to more complex networks featuring multiple subnets and VLANs. Whether you’re a seasoned expert or new to network management, our guide aims to equip you with the knowledge and tools needed to navigate these challenges with confidence, ensuring your network remains robust, secure, and efficient.

We’ll discuss the following:

A subnet, or subnetwork, is a segmented portion of a larger network, designed to optimize performance and improve security. By dividing a network into smaller, manageable subnets, traffic can be efficiently routed, reducing congestion and enhancing network security. Each subnet operates under a unique address, facilitating organized data routing within and between networks. 

Subnets are essential in complex network architectures, enabling administrators to allocate IP addresses more effectively and isolate network segments for specific purposes or departments.

A VLAN, or Virtual Local Area Network, is a technology that creates distinct broadcast domains within a single physical network infrastructure. It allows you to segment networks into separate, isolated groups at the data link layer (Layer 2) of the OSI model. This segmentation enables improved network management, and enhances security by isolating sensitive data traffic. What’s more, it reduces overall network congestion by limiting broadcast traffic to specific VLANs.

VLANs provide the flexibility to group devices together based on functional, departmental, or application-related needs rather than their physical location, facilitating more efficient and secure network operations.

How to Start Monitoring Networks with Subnets and VLANs

Frequently, I encounter questions regarding the optimal deployment of Domotz agents in networks featuring subnets and VLANs.

How many Domotz agents should I use on networks with subnets and VLANs?

How should I install an agent?

To address these queries, I’ve compiled this guide to simplify network monitoring with Domotz across various configurations.

We’ll explore suitable setups for diverse network structures, aiding you in determining the most effective deployment strategy for new installations.

I get these questions a lot which is why I thought it would be useful to write up a quick guide on monitoring networks with subnets and VLANs. This guide covers how to install our network monitoring software in different types of networks. We’ll cover a variety of setups and use cases.

Determining Your Network Configuration

Start by answering these crucial questions to understand your client’s network setup:

  • How many subnets does my client have?
  • Are any of these subnets VLANs?

With these details, navigate to the section most applicable to your client’s network scenario:

  1. One Subnet, no VLANs
  2. Two or More (routed) Subnets, no VLANs
  3. Two or more Subnets (VLANs)
  4. Multiple Network Interface Cards

This case covers a network structured on a single subnet (with a maximum of /22 subnet mask –, wired or wireless, where all devices are reachable on Layer 2.

If your client has a /16 network Domotz also supports this.
If you need to enable /16 network scans, contact our support team at

A network configured with one subnet and no VLANs is the most common case scenario when dealing with local area networks.

For example, ( is a classic class C network.

In the case of a network with one subnet and no VLANs, you can monitor all your devices with Domotz, you would need only one Domotz Agent.

Monitoring networks with subnets and VLANs

Read more in our Help center.

For networks spread across two or more subnets accessible via a router or VPN, for example, and

In this scenario, consider the following two deployment options:

  • Option 1 (Recommended): Deploy a Domotz Agent for each network. In other words, you deploy two Domotz Agents, one agent per network.
  • Option 2 (Alternative): Deploy one Domotz Agent for one network and define the other as a “Private Subnet” within Domotz. 

This option is not available in the connected VPN that does not use a private IP addressing scheme. In other words, if it’s using a non-RFC 1918 compliant name, then this option is not available. Learn more here.

Note that there are some limitations on – the private subnet:

Learn more about how to add a “Private Subnet” in your Domotz Agent.

This guide covers a network with two or more additional VLANs defined on a managed switch.

Let’s assume that your client has the following VLANs:

  • (managing VLAN – untagged)
  • (VLAN 20 – VLAN tag/ID 20)
  • (VLAN 30 – VLAN tag/ID 30)
  • (VLAN 40 – VLAN tag/ID 40)

In this scenario, you only need one Domotz agent to monitor all your VLANs:

Monitoring networks with two or more Subnets (VLANs)

The VLAN configuration you use in Domotz depends on the operating system the Agent is installed on. If you need to configure VLANs, we advise you to install the Linux Agent or purchase a Domotz Box because they are VLAN-ready.

Learn all about configuring VLANs in Domotz in this guide.

This case describes networks accessible from a server with multiple network interface cards. This is a network with two or more subnets that you can reach in layer 2 from a single location even if they are located in separate switches.

This scenario involves the server with multiple network interface cards.

Each of them is configured with a static IP address suitable for monitoring each subnet. Afterward, they are attached to the corresponding network appliance.

In this case, a single Domotz agent is installed on the server, and it will be able to monitor all the subnets connected to its network interface cards.

Server with multiple network interface cards

Further Assistance

Should you have additional questions or need further guidance on configuring VLANs, installing your Domotz Agent, creating network topology diagrams, or understanding the benefits of network monitoring software, don’t hesitate to reach out to our support team at

This guide aims to streamline your network monitoring strategy with Domotz, ensuring you’re equipped to handle networks of varying complexity with confidence.

Learn more about configuring VLANs and installing your Domotz agent.

Learn more about how to make a network topology diagram and the top reasons to use network monitoring software.

Further reading:

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