Originally Posted by timwilky

/30 refers to the number of bits in the network section of the subnet mask. or that there are two bits to make up the host section.

A subnet is 32 bits normally expressed in the / notation or as 4 8 bit octects in decimal, ie 255.255.255.0 is 11111111.1111111.11111111.00000000 in binary or /24

This is the minimum needed to provide 2 usable addresses and is therefore the most suitable for a point to point network link etc. Those 2 bits would give you 4 addresses.

0- Network address
1-End A
2-End B
3-Broadcast address

Lesson over