DoS Denial-of-Service (DoS) attacks are a type of network attack. A DoS attack results in some sort of interruption of network service to users, devices, or applications. There are two major types of DoS attacks: Overwhelming Quantity of Traffic - This is when a network, host, or application is sent an enormous quantity of data at a rate which it cannot handle. This causes a slowdown in transmission or response, or a crash of a device or service. Maliciously Formatted Packets - This is when a maliciously formatted packet is sent to a host or application and the receiver is unable to handle it. For example, an attacker forwards packets containing errors that cannot be identified by the application, or forwards improperly formatted packets. This causes the receiving device to run very slowly or crash. DoS attacks are considered a major risk because they can easily interrupt communication and cause significant loss of time and money. These attacks are relatively simple to conduct, even by an unskilled attacker.