Introduction

I hope you enjoy the great monitoring software Check_MK. If you have a big environment with lots of hosts and services distributed over dozen of sites (company locations) , you might have already configured your Check_MK to use the distributed monitoring in WATO. I assume that you have got a master and some slaves. The master in terms of Check_MK is the host, which you are using to configure your whole Check_MK installation and to look at all hosts and services, whilst slaves are those hosts that receive the configuration from the master and which the master gets the monitoring results from.  Distributed monitoring is an extremely nice and powerful feature of Check_MK that allows you to keep your configuration at one place and that takes care on distributing the changes on the configuration to the slaves. Also it’s very easy to connect a new slave to the master site.

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In some distributed environments and with a lot of configured users and connection to Microsoft active directory configured in Check_MK times to distribute the changes from the master to all slave sites grow up strongly. Check_MK distributed monitoring uses Apache web server acting as reverse proxy. Sometimes one of Apache web server’s instances doesn’t return data within a pre-defined time range. In such cases you can get the error like this while trying to replicate your slave with the master site:

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