0 a number that is obtained by adding all the numbers in a piece of electronic data, used in order to check that the data is correct --
In order to compute the checksum, multiply each of the digits by either 3 or 9, alternating each time.
The checksum field is the 16 bit one's complement of the one's complement sum of all 16-bit words in the header and text.
When received at the destination, the checksum is recalculated, and compared with the one in the packet.
For example, after line 140, the checksum was expected to be 149, then after line 290, it was expected to be 21, etc.
Such initialization thus generally takes a long time and involves cryptographically locking each monitored object and the checksum databases or worse.
The third checksum is in the directory file sets.
When a packet arrives at a router, the router calculates the checksum of the header and compares it to the checksum field.
Consequently, the router must calculate a new checksum.
