In one embodiment, a processor-readable medium storing code representing instructions that when executed by a processor cause the processor to update, at a memory location, a first flow state value associated with a data flow to a second flow state value when at least one of a packet from the data flow is received or the memory location is selected after a time period has expired. At least a portion of the packet is analyzed when the second flow state value represents a flow rate of a network data flow anomaly.