The mod_deflate module provides the DEFLATE output filter that allows output from your server to be compressed before being sent to the client over the network.
Aren't you miss-understanding the usage of this mod?!
Anyway, none apache module will ever stop DDoS attacks. Your sites will probably stay alive and on-line with some apache mods for longer time, but it's not a solution, as soon as Apache will still get the requests from attackers and spent time,CPU,RAM on answering them .