They know that anyway. The longer and more severe an attack is, the more damage it's likely to do. A host may be able to sustain 30Gbps for a minute or two, but

They know that anyway. The longer and more severe an attack is, the more damage it's likely to do. A host may be able to sustain 30Gbps for a minute or two, but not for 5 minutes. If 5 out of 10 servers are being attacked, you can probably handle traffic at 50% capacity for a while, but not forever.