What is the difference between agent and agentless monitoring?
Agent and agentless monitoring are the two methods used for infrastructure monitoring you’ll see in the market today, and while they have their differences, both are valid options when you’re looking at monitoring platforms.
Agent: While sometimes designed for a specific system, agent monitoring can also be vendor agnostic and uses a small client installed on servers to collect data and metrics. This typically allows for richer data and more flexibility.
Agentless: Relying on SNMP, WMI, SSH, NetFlow, and other protocols to retrieve metrics back to monitoring software, agentless monitoring is lightweight and is often enabled by default on your servers or devices. For specialized hardware (like routers, switches and load balancers), this is usually your only option.
There are pros and cons to each method, but it’s important to understand both options because you will likely need to use a mix of both. The effectiveness of your monitoring can oftentimes be measured by reviewing the balance between depth and coverage, but we’ll go into more detail about this throughout the guide.
The Pros and Cons of working with Agent or Agentless monitoring
Agent and Agentless offer a lot of pros and cons across a broad range of IT concerns, so here are some considerations to make before your final decision:
Typically, agentless monitoring requires a single ID with administrative or domain global access to continuously gather data which can create a security weak point. For this reason, agentless monitoring isn’t usually recommended for organizations that have higher security requirements.
Agents which are installed individually do not have global access to the network, meaning that if one is compromised, the entire network is not compromised. This makes agent monitoring more secure and better for a high-security environment.
Agentless monitoring systems are typically lightweight and less intrusive than agent monitoring systems, and therefore provide more flexibility. In addition, the use of APIs and WMIs often means the monitoring is provider agnostic and can be used in highly varied IT environments.
While modern agent-based monitoring systems are fairly lightweight, they do often still use some resources from the system they are installed on. In addition, depending on the provider, certain agents might not work with devices or systems.
Depth of Data
Agentless monitoring works well for some systems, but it does lack some deep dive capabilities, and therefore, the data you can collect using agentless monitoring is often not as robust as agent monitoring.
With Agent monitoring, it’s possible to get in-depth data that is much richer than agentless monitoring gives you. Custom applications are also usually easier to monitor with agent monitoring due to the deeper data capabilities.
Ease of Use
Deployment and maintenance both tend to be a little bit easier with agentless monitoring due to their lightweight design. However, they often have a heavy dependency on the network, and in the case of a network failure, are more likely to fail as well.
Agent monitoring takes more time to deploy and maintain than an agentless system, but typically it’s easier to run automated diagnostics and remediation through an agent, both of which provide a significant ease to operations. In addition, it’s important to note whether or not agents have the ability to auto-update, especially in larger environments.
So should your team use agent or agentless monitoring?
The short answer is that you should be using both.
When it comes down to it, the highly complex environments that exist in the IT space today require some level of both agent and agentless monitoring. Typically, organizations will use agent monitoring for the depth of data it provides and agentless for the flexibility and ease of testing.
Questions to help guide your decision
Finding what works for your organization is something you’ll have to do over and over, so we recommend using a review cadence where you consider these questions regularly as your organization matures.
Here are some things to consider when reviewing agent or agentless monitoring software:
- What level of data does your organization need to collect?
- How complex is your IT infrastructure and is it centralized or distributed?
- Does your operations team need a high level of control over monitored devices?
- Is summarized visibility sufficient for your environment?
Our recommendation is to do this as regularly as your team needs, whether that means any time you change or advance your infrastructure or whenever you bring in a new tool.