Let's talk about how proxies operate a bit. We'll cover three things here:
- Synchronization of the configuration
- Synchronization of the collected data
- Operation during maintenance
By default, proxies synchronize the configuration once per hour, and this period can be set in the zabbix_proxy.conf configuration file. Look for the parameter named ConfigFrequency, which by default will look like this:
# ConfigFrequency=3600
This means that a Zabbix proxy can lag in configuration up to an hour, which might sound scary, but once a production installation settles, the configuration usually doesn't change that often. While testing, you might wish to decrease this period, but in a stable production setup, it is actually suggested to increase this value.
The collected data is sent to the server every second by default. That can be customized in the zabbix_proxy.conf file with the DataSenderFrequency parameter.
Regarding host and host-group maintenance, when a host is in maintenance without data collection, data is still sent by proxy, but the server discards it. This way, changes in the maintenance status do not suffer from the default one-hour delay for a configuration sync.