Agent vs Agentless Monitoring - What are the Differences & the Best Tools & Software

Agent based vs Agentless monitoring software and tools for Monitoring your network infrastructure, Servers and computers is a timeless debate that many admins and engineers constantly fight over. On top of that, Software vendors say they support agentless monitoring and in all reality, its only a partial truth – as in-depth statistics at times need agents installed in order to gather and combine that data.

From our experiences, having a combination of both agent based and agentless monitoring solutions will cover an array of services, systems and applications. We're going to cover the differences between the methods of gathering data from your systems and some pro's and con's of each.

Agentless Monitoring

We'll start with Agentless Monitoring, as this method seems to be the most popular of the the two methods. This type of monitoring usually relies on SNMP, WMI, SSH or any other protocol to relay information to the central monitoring software with data and statistics about the system.

Although it may seem that easy, hardware and software manufacturers have integrated these built-in features to relay information in the production process. These Management agents are embedded within the software/hardware and allow you to centrally manage and monitor without any additional agents installed.

So technically speaking, they're Agentless, but the software agent is really just built into the platform natively.

Agent Based Monitoring

On the other hand, Agent-based Monitoring allows you to collect, analyze and process significantly more data from a given system. This is usually a given, considering that software and hardware vendors provide agents that are specifically designed for their respective platform and have programmed the agent to interface with it specifically.

This could be seen as a positive or a negative, depending how you look at it.

The positive side of having agents that are vendor specific is that they give you insights that agentless monitoring cannot accomplish. On the Negative side, you are locked into that platform and migrating to a new platform will result in losing that in-depth data that you once had.

Important Factors to Consider

There are several factors to always consider when looking into a Monitoring solution or purchasing new Software or Equipment. Monitoring that device is going to be crucial and 100% necessary if your an IT Admin or Engineer who cares about your career.

Does your Software/Hardware systems provide you with an Agentless monitoring solution (via API) or do you need to use proprietary agents to monitor them? If so, you may want to look further into your monitoring system and see if those interface correctly and have the compatibility with those given systems.

Here are some common IT Infrastructure Equipment and Components that can be monitored in an Agentless Manner:

Networking Devices (Routers, Switches, Wi-Fi, etc):
SNMP can be used to access critical information of your Networking Devices including Utilization, CPU Load, Memory Usage, Bandwidth and more!
Servers:
SNMP, WMI, SSH, HTTPS are all protocols used to Monitor Server operating systems including Windows Servers, Unix, Linux and many others!
Flow Devices:
Netflow, sFlow, IPFix, jFlow and rFlow are some of the Flow protocols that can give you insights into whats happening in your Routers and Switches, including Cisco, Juniper and other major manufacturers.
Storage Devices (SAN & NAS):
Storage Arrays can be monitoring via SNMP and other protocols including SMI-S if supported.
Virtual Machines & Hyper-Visors (Vmware, Hyper-V, Xenserver):
WMI, CIM and other protocols can be used to Poll Hyper Visors for information.

As you can see, many mainstream IT Infrastructure components, hardware and software packages and solutions have an array of Agentless monitoring capabilities. With these protocols already in-place and supported, the only thing left is finding a good IT Infrastructure monitoring solution to manage everything centrally!

We've compiled a large list of tools and software for Agentless monitoring that you can try here!