$192\mathrm{.}169\mathrm{.}1\mathrm{.}1,10\mathrm{.}0\mathrm{.}0\mathrm{.}1,$ and $10\mathrm{.}0\mathrm{.}21\mathrm{.}1$ are all examples of:

IP addresses

Computer identification numbers

Serial numbers

Port numbers