Choosing between active and passive items
Even though we discussed Zabbix agents being active or passive, an agent really is neither one nor the other—the direction of the connections is determined by the item level. An agent can (and, by default, does) work in both modes at the same time. Nevertheless, we will have to choose which item type—active or passive—to use. The short version—active items are recommended.
To understand why, let's compare how the connections are made. With a passive agent, it is very simple:
One value means one connection. An active agent is a bit more complicated. Remember—in the active mode, the agent connects to the server; hence, the agent first connects to the Zabbix server and asks for a list of items to be monitored. The server then responds with items, their intervals, and any other relevant information: