Best thing to do is turn off icmp aka ping on your cable router from external sources. Majority ddos but not all use a ping flood method. If you do get ddos just turn router off for 15 mins and you will have a new IP. There is not much you can do as a user except call your ISP and have them trace what internet provider they are using and hope they investigate. At a minimum they lose their internet service provider, but you are at the mercy if your ISP feels like doing the leg work on your behalf.