Mobile Banner Ad Design

I need to know how you can make a mobile banner ad design.

I have designed a lot of web banners at 72 DPI. Is everything for a mobile banner the same except for the DPI? What should the DPI be?

Thanks!

You have to bear in mind high resolution displays on newer iphones and android smartphones. You can use a vector svg and ignore dpi entirely if you’re happy to ignore older mobiles, or serve up 72 dpi bitmaps as an alternative to them.