Use row-table (e.g. A21) for exam halls, T-number (e.g. T15) for SPER. 'Last table' is optional, use it if you want to calculate a range of IP addresses.
Use Slackbot! /ajh 129.125.123.45 to find matching table /ajh 3-B23 or /ajh SP-T5 to find the corresponding IP address