An IDS is an example of what type of network device?

Intrusion detection systems are considered passive systems because they cannot block traffic. Active systems like firewalls, IPS, and proxies all have the ability to directly interact with and stop or allow traffic. Air gapped devices do not have a physical connection to a network, or they are on a separate network that is not connected to other networks. Fail-closed devices stop traffic when they fail. Most IPS systems are not deployed inline since they do not need to be interactive and having them inline only creates another potential failure point.