My question is simply, if I check an internet check sum for a UDP packet and then receive a packet and it matches, can I be 100% sure there are no bit errors? (deliberate or accidental)
As in: I know UPD packet error checking prevents false negatives, but how do false positives (if possible) occur?
False positive == flagging it as ok after check sum comparison but there is in fact still errors.
False negatives == flagging as an error guarantees an error.
(NOTE:I didn’t define false positive, and negative to aid my the person answering me as much as to help make this question as useful as possible for others later down the road. I in no way wish to insult anyone’s intelligence.)
No, you cannot be sure. There are multiple different packet contents that will have the same checksum. This is a trivial consequence of the pigeonhole principle.