DOS Security and fast loadtime

[outsiderlv]

I have my own server located in data center with 100Mbps in my country.
O/S Linux ubuntu
Webserver Apache

What should I do to protect against DOS attacks?
And what should I do to make my website load faster? It is pretty optimized and the loadspeed is good, though I would like to know what should I do with my webserver to load the websites faster (i know that lighttpd is faster but I need information about Apache so don't tell me to change webservers, please).

[Grumpy]

It depends on the type of dos attack you are receiving. So, it's hard to say a cover statement that will solve everything except that there are ddos/dos specialist services out there. These cost a LOT of money though. You're looking at minimum of couple hundred a month to tens of thousands a month for larger attacks. Things also like search flood is in place for the purpose of preventing dos.

There are php optimizers and tools to help IPB run more efficiently. IPB naturally supports apc, xcache, eaccelerator (i think), and memcache (choose one). These are some of the options you have to speed up php processing. There are also options to send static files via an engine other than apache such as nginx, varnish, lighttpd, etc (again, choose one) on top of apache (they are not necessarily replacements for apache!). And lastly, there are solutions which reduce load on your database with things like sphinx. There are lot of these threads in this forum covering these topics, so I suggest you read them if you're looking to do so. And really lastly, but noted separately as it's not the same, but there is a choice to use a CDN. These will speed up your performance globally (but not locally) and will also reduce the need to handle everything with your own server but a 3rd party.