Where can I find the document on the different between agent vs agentless?
Not sure there is one?
The difference is fairly obvious, isn't it? On one hand, you have an agent. A piece of software that runs locally on the thing you want to monitor. On the other hand, you have agentless, which means all monitoring would have to be done remote (through snmp, etc).
While your answer addresses the obvious, I don't think it really gets to the heart of the question.
- Lightweight, WMI or SNMP based
- Basic system gathering
- Requires the installation of a lightweight agent
- Local database retains information if connectivity is lost
- Provides greater detailed data collections
- Required to monitor applications, processes, services
I am sure there are other benefits to both sides but all I can think of at the moment.
I think both are needed in a more complex network, let say that your infrastructure have multiple networks with some apliances in the middle like firewalls and load balances.
With Agent Based monitoring you have the state of the application localy.
With Agentless you can have the state on other networks.
So lets say that the customer modify his application, and the application begins to require a query from the user that the firewal consider as a treath and blocks. With a combination of the monitoring strategies became clear that the problems is with the firewall becuase you are going to have one alarm comming by the agentLess monitor and none comming from the Agent