You’re monitoring many hosts at many remote locations. A link to a location dies and to you and your Zabbix Server, everything is offline at the location! Zabbix Proxies to the rescue!
Zabbix Server ↔ Zabbix Proxy ↔ Host
To ensure consistent data gathering, you can utilize Zabbix Proxies. Proxies act as intermediaries and collect performance and availability data on behalf of the Zabbix Server. They are able to perform the same data gathering tasks as your Zabbix Server. They do so into their own database, which means they are autonomous. They temporarily store the gathered data locally and send it to your Zabbix Server as soon as possible.
If a Proxy becomes detached from your Zabbix back-end, it will continue gathering and receiving data from hosts that are assigned to it. When connectivity to the proxy is re-established, the Server and the Proxy will exchange any missing data. The Proxy gets up-to-date configuration and the Zabbix Server receives the data gathered on the Proxy while they were disconnected from each other.
The Zabbix team has written a thorough guide for setting up a proxy which you can find here: https://www.zabbix.org/wiki/InstallOnCentOS_RHEL#Proxy_Install
Check up on your Proxies
As with any other host, a proxy can and should be monitored. They perform a vital task to your Zabbix ecosystem.
The standard “Template App Zabbix Server” be used to monitor performance, cache and other vitals. It serves to give you a good overview of what’s going on with your proxy and the health of it. Keeping it running smooth is key since it is now just as important, to your remote hosts, as the Zabbix was before.
Triggers are useful here for getting alerts about proxy health and staying on top of potential problems that could hinder the gathering of your data. Your proxy should be regarded as almost as important as your Zabbix server.