I'm currently prepared my BCMSN certification Exam.
I would like to know what is the difference between forwarding paquet to the Null Interface (silently absorb paquets, whitout farwording them) and simply drop the paquet without sending ICMP paquet to the sender....
They are generally doing 2 different things. When a packet is dropped but no ICMP packet sent back this is usually for security reasons to not give away any more information than is needed.
Routing to Null0 is usually used to
1) Stop routing loops - IGP's
2) Place a route into the IGP routing table so that BGP can then advertise it out.
Is there a specific context you were thinking of ?