Bug with Servers

My friends server, gets DDoS'd quite often, and whenever it gets hit off, the server comes up with this message "Internal Exception: io.netty.handler.timeout.ReadTimeoutException" when you try and join, i have found a temporary fix for it, which is rebooting the server. I have done a bit of research and it says something about it having chunk errors and that's what makes it happen, but anyhow, i hope this gets fixed because its a pain in the behind

P.S. It also happens with Minecraft Version 1.7.4 & 1.7.2