Ask HN: Are there any effective measures against DDoS attacks?

The company who I work for has taken on a lot of new business lately and while, thankfully, we've never been a target of any attacks before now, I'm a little concerned that we might not escape indefinitely. As a large portion of our business is online and due to our business becoming more and more high profile in recent years, I'd like to have some kind of disaster recover plan in place for DDoS attacks (even if the IT director and/or CEO dismisses any contingencies I recommend, I wouldn't be doing me job right if I didn't at least investigate this potential).

So I'm basically just looking for some advice in any hardware recommendations and ways to react when such an attack is under way.