Changing your IP address by changing your MAC address can only work in the short-term when dealing with DoS attacks (Denial of Service attacks), especially those of the DDoS (Distributed Denial of Service) variety. At any rate, there are more permanent, long-term means to deal with DDoS prevention. Instead of having to deal with DDoS as it's happening, it's best to prevent it from ever occurring in the first place. VPN or a Virtual Private Network is your best option when it comes to dealing with this issue, to be true. Among the quality VPNs out there, the daringly named "HideMyAss" is by leaps and bounds the best in the business.
Safeguard your networks
It's highly recommended that you safeguard your computing and networking needs by buying the product and hiding your IP address from prying eyes while enjoying a relatively faster connection to the Internet thanks to the caching capabilities of this particular VPN brand. At any rate, HideMyAss (or any other alternative VPN you have available in your region or area that should do the trick in keeping you safe from DDoS attacks and floods) has a huge list of servers available that are organized in accordance to their geographical distance from you. Therefore, by going the VPN or proxy route, you'll remain anonymous and free from DDoS targeting.
Switch IP Address
More to the point, by acquiring a VPN connection, you can use its dashboard services to do some evasive maneuvers against those who want to shut down your machine and make the Internet completely inaccessible to you, such as the ability to schedule automatic IP changes, doing IP changes as you wish them done via your control panel, and making quick location changes whenever possible. This will keep your attackers confused when it comes to targeting your IP address for a DDoS attack, especially in light of the fact that DDoS is only effective when it's done in a focused manner.
VPN is the difference between being blasted by a machine gun as a stationary target and being gunned down as a moving target with cover and camouflage. The best VPNs out there will enable you to change your IP address settings at will without turning off your modem or affecting your ping. Of course, not all servers are created equal. Some might jump around between 70 ms to 100 ms, but for the majority of servers, a quality VPN will keep your ping as steady as a rock, no matter how many games you play or live videos you stream. Some compromises might be made... like download speed decreases and whatnot... but if you're a regular DDoS victim, they're minor inconveniences.