A checksum is used solely to see if a file has changed or to see if two files contain exactly the same data. The chances of two different files having the same checksum is very, very small.

If you change a file in any way, even by one byte, the checksum will change.

RIP messages are wrapped in a UDP package, which already has a checksum.

A checksum is used to determine that the information sent using the protocol has not been corrupted en-route.

Only TCP will automatically discard a packet with a bad checksum. UDP packets have a checksum field, but it is rarely used, and then only by the application (not UDP itself)

A checksum (also known as a hash sum) is a small size datum computed from a block of digital data. One would use a checksum to detect errors that could have been introduced during storage.