How are custom checks created in Zabbix?

Custom checks in Zabbix are created by utilizing user parameters defined in the Zabbix agent configuration. This approach allows users to extend the functionality of the Zabbix agent by defining specific checks tailored to their environment or application needs. User parameters enable the execution of custom scripts or commands on the host where the Zabbix agent is running, allowing for the collection of specific data that might not be covered by default items.

When configuring these user parameters in the Zabbix agent configuration file, you can specify the command to execute and the associated item key. This customization enhances monitoring capabilities by allowing the capture of metrics or status information unique to the particular system being monitored.

The other options, while they may represent potential avenues for interaction with Zabbix, do not specifically address the method of creating custom checks in the way that user parameters do. For instance, importing scripts from external sources could provide additional functionality but does not directly translate into the structure of custom checks as defined within Zabbix. Similarly, manually entering check criteria or utilizing built-in templates refers to existing monitoring capabilities rather than the customized and user-defined approach enabled by user parameters.