Hello,

we just found out that agents with multiple hosts are not fully compatible with proxy group solution (support case MG-445). We would like to have this rectified as it poses major thread to stability of the monitoring. 

Description of the problem:

We have agents with multiple hostnames in Hostname variable in their config file. For each of these hostnames we then have separate host in Zabbix. The most standard example is one hostname for OS host and another one or multiple ones for DB instances (Oracle, MSSQL and so on). All these hosts have assigned the same IP and port in the agent interface (OS hosts for active check monitoring and DB hosts for availability check via TCP port check). The problem occurs when these hosts are monitored by proxy group and when load balancing switch one of the hosts to different proxy. Now multiple hosts with the same interface are monitored by multiple proxies and each proxy thinks that the host is monitored by other proxy. Essentially disabling monitoring for those hosts. 

Proxy group load balancing should be updated to take this into consideration and always keep such hosts on the same proxy.