Question

flags in ipv4 header

Networking, IPv4, Ping

the 3 flag bits in ipv4 header are.

1 - whether this fragmented part is last or not.
2 - to fragment a message or not.
3 - reserved.


so if my message length is 500bytes and maximum segment size is only 200bytes and i want to send this messase but MIDDLE BIT VALUE IS 1.(that is do not fragment the message) then wat will happen fragmentation occurs or some error occurs or what??????

If you set "Don't fragment" the packet. Then when the packet gets to a router that has a smaller MTU (than it received the packet on), it will drop the packet as it will not be able to process it.

Generally you dont need to worry about that flag, unless you are trying to work out what is the largest packet size you can send between point A and point B.

-- Nephi