A flat fee, also referred to as a flat rate or a linear rate, refers to a pricing structure that charges a single fixed fee for a service, regardless of usage.[1] Less commonly, the term may refer to a rate that does not vary with usage or time of use.
Synchronous: interrupt occurs as a result of current process, otherwise asynchronous. User requested: interrupt occurs because of direct result by user task, otherwise coerced. Maskable: if desired the interrupt can be disabled by a user task, otherwise unmasked.
When a packet arrives from the network, an interrupt from the network card is serviced by the computer. Then a Deferred Procedure Call (DPC) is queued, and must make its way through the drivers. If any form of security is used, the packet may have to be decrypted, or the cryptographic hash verified.