How do I identify IPs on my network? And another Q

RouterOS Beginner Basics
5

you can search on gogole the first 3 HEX value on MAC address for know the manufacturer.
For example 00:0C:48:xx:xx:xx is MikroTik.

If the 2nd number of the first hex value IS NOT 0, 4, 8 or C (or “c”) the MAC is a random address.
http://forum.mikrotik.com/t/check-if-string-is-contained-in-a-file/160452/1