Yes, the discrete Fourier transform (DFT) detects N frequencies in parallel, where N is the block size, and you can disregard the uninteresting frequencies. The fast Fourier transform (FFT) is an efficient algorithm that computes the DFT. For detecting M frequencies where M << N, the Goertzel algorithm requires less computation than the FFT. Also, the Goertzel algorithm allows targeting more exact frequencies regardless of the sampling rate (Fs), while the FFT's bins have a fixed spacing of ±Fs/N.
As with everything, there are trade-offs associated with these three options.
The load balancers share one public IP address. Only one server at a time is assigned that address. To failover:
1. Physically isolate the failed load balancer by removing power and/or disabling its Ethernet port on the switch.
2. Assign the shared public IP address to the new active load balancer.
3. Broadcast an unsolicited ARP reply from the new active load balancer.
The decryption key doesn't construct data anymore than the combination to a safe constructs the papers inside it. The data exist independently of anyone's ability to read them.
As with everything, there are trade-offs associated with these three options.