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Any kind of interpolation is faking the data you don't have - that is, you are guessing what might the data between the sampled points you have be. Of course, you can make good guesses, considering typical band-limited signal, so no big changes possible between samples, etc.
There are many ways how to do 'interpolation'. One is just repeating the existing samples some n-times (this is definitely the worst way). A little better is linear interpolation between samples (this also allows fractional upsampling). The best is of course a properly-designed low-pass filter. (In theory, all these methods are actually a sort of a filter, either a Zero-Order Hold, a weighted moving average, or a (windowed) FIR/IIR).
But, just zero stuffing (A0B0...) is *not* enough for proper upsampling without the accompanying filter.
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