A 3200 - bit long TCP packet to the IP layer, and a 160 - bit first become a datagram, after the Internet through a router connected by two LAN, but the second longest LAN can transmit data in a data frame part is only 1200, so the data reported in the router must be shard, asked the second LAN to its top to send how many bits of data (in this case, the "data", of course, is LAN saw data)?

The answer to the 3840, each piece is divided into 1400, but fragment offset regulation size must be 8 bytes integer times, the answer is wrong? Why is the answer?