In computer networking a packet drop attack or blackhole attack is a type of denial-of-service attack accomplished by dropping packets. Computer networking is the Engineering Discipline concerned with communication between Computer systems or devices Networking routers In Information technology, a packet is a formatted unit of Data carried by a Packet mode Computer network. The attack can be accomplished either selectively (e. g. by dropping packets for a particular network destination, a packet every n packets or every t seconds, or a randomly selected portion of the packets, which is called "Gray hole attack") or in bulk (by dropping all packets).