A node in ESIA refers to any equipment, hardware or software, that is being monitored.
A plugin is the name given to a test that can be applied to a node.
For example, the “Check_DNS” plugin tests the DNS service.
A pattern is a group of plugins. They have been created to make it easier for you to manage them.
In practical terms, this allows you to group together a set of plugins under a pattern. When you need to make changes to a plugin for all your machines, all you have to do is modify the pattern (which automatically recognises the nodes where the chosen plugin(s) are located.
Unity is a software and hardware package that makes it very easy to deploy monitoring or perform audits at key locations. The package operates via a secure tunnel, so you can bypass a firewall and deploy 'active' monitoring.
Unity is in fact a monitoring gateway providing access to protocols such as SNMP, IPMI and ILO.
This is the name of the OS installed on the Unity.