A student hаcks intо the system used tо mаnаge lab cоmputers at her university. She modifies the system so that a malware application is installed on every lab computer. On the first day of the final exam period she configures the malware so that every lab computer sends continual packets of random data to the server used for online exams. The amount of data overwhelms the server and online exams are cancelled while the problem is investigated. This is best described as a/an ________ attack. (Give the full name, not just an acronym.)