This disclosure describes techniques for employing a reusable acknowledgment in communications among network devices. The techniques include generating a reusable negative acknowledgment (NACK) in response to a request for data that are unavailable. The reusable NACK may be sent as a response for at least some additional requests for unavailable data, rather than generating a new NACK for each request. As such, the reusable NACK may help decrease the computational load for a network device. In some cases, the use of a reusable NACK may help lessen the impacts of denial-of-service type attacks across a network.