Just want to clarify, there are 2 things being talked about over here 1. Mac Address 2. IP address. A Mac address cannot really be changed at best it can be spoofed, Its basically a serial number. When you talk about changing your IP I imagine it is because you are getting banned for trying to scrape a site. What you need is to rent some proxy servers and have them run in parallel. 5 is usually more then enough for the average small businesses.