Limiting Apache requests per IP Address is always a good idea. It can prevent site issues where people attempt to DoS/DDoS you or resource hungry bots slowing your site down. Every Apache install should run mod_limitipconn which allows administrators to limit the number of simultaneous requests permitted from a single IP address. It goes very well with mod_evasive which does a very similar job but with a slightly different focus. I’ve run both with no issues. Here’s my mod_evasive threads; 2010, 2013.
Installing on CentOs/Fedora is easy. (Install the EPEL Repo)
yum install mod_limitipconn
This will create you a /etc/httpd/conf.d/limitipconn.conf file. Tweak and restart Apache.
Installing from source with APXS isn’t much more difficult
tar xavf mod_limitipconn-0.24.tar.bz2
I edited the config file/etc/httpd/conf.d/limitipconn.conf and added
This simply limits all users to 10 simultaneous requests. Of course you can be clever and add options specific to directories / MIME Types and anything else supported in Apache, like this;
OnlyIPLimit audio/mpeg video
Check out the documentation for more information.