I want to get information of how to maintain large number of servers in a big environment. Let me explain by an example

Let say there are more than 200 server and all of them are kind of running the same services e.g. web server, mail server, file ftp server etc. and they all need to be check and monitored on daily basis and check if anyone of them have problems.

So what is the best possible solution for this kind of server environment.