Ping and Network driver

Squier

I have two question.

1)I have my network driver: mynet0, his ip address: 192.168.1.0. Why, when i call ping -I mynet0 192.168.1.0 function ndo_start_xmit from struct net_device_ops is not caused, and this function is caused only when i call ping -I mynet0 192.168.1.X, where X != 0?

2) Why if i return NETDEV_TX_BUSY or NETDEV_TX_LOCKED in function ndo_start_xmit kernel crashed?