hahaha....thank you so much for your patience and vivid examples. guess I have some idea for nand. that is pretty much like software ghost doing for pc os, making an image of one partition or the whole disk, just in case we need to back to the second when we created the image, right?
As to root or not root, i see your saying. May I say that unroot is not officially turn back your phone to "unrooted", just restore os to the stock, and sprint cannot tell if you rooted or not, correct?
So if I wont bring phone back to Sprint, so they cannot tell if the phone is root or not. does that mean that they cannot detect your phone root status on the air, furthermore, they cannot ban your phone since they dont know if you root you phone or not?
anyone mind to see if my understanding is correct? thank you