In the last post we have seen how to check the mtu on windows vista. In this post we will see how to set the DF big on a packet.

On command prompt ping yahoo.com -f -l 1460; you will see the reply. Now ping yahoo with 1500 bytes, you receive packets need to be fragmented. -f is used for donot fragment.

Pinging yahoo.com [206.190.60.37] with 1500 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.