Some routers, including UAR, handle this potentially fatal situation by refusing to start up. This network range is used until a router is contacted and the real network range is determined. Network ranges on different physical cables may not overlap , therefore routers should not be configured with network numbers in the range 255.0 to 255.254. One of the fields in the DDP packet header is a 16-bit checksum. This is used to protect packets against data corruption in intervening routers and noisy networks.
Macintoshes always default to sending DDP packets with the checksum field disabled.
It is strongly recommended that routers have checksum code enabled. The University of Melbourne.