# Networking - Subnetting - Discussion

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"Everything you can imagine is real."
- Pablo Picasso
4.

What is the maximum number of IP addresses that can be assigned to hosts on a local subnet that uses the 255.255.255.224 subnet mask?

 [A]. 14 [B]. 15 [C]. 16 [D]. 30

Explanation:

A /27 (255.255.255.224) is 3 bits on and 5 bits off. This provides 8 subnets, each with 30 hosts. Does it matter if this mask is used with a Class A, B, or C network address? Not at all. The number of host bits would never change.

 Nikhil said: (Sat, Feb 8, 2014 12:17:19 AM) 255.255.255.224 i.e Binary of 255 is 11111111 and Binary number of 224 is 11100000. Here 1 Represent On bit and 0 represents Off bit. Then how to calculate Host Id. See Here, Formula Host Id = 2^off bit - 2 i.e 2^5 = 32 - 2 = 30. And Net Id is = 2^on bit = 2^3 = 8. That's why Answer is 30.

 Rahul said: (Wed, Mar 11, 2015 05:05:59 PM) Simple. = 256-224 = 32. And here first add is network add and last one is broadcast so we are supposed to subtract these two add from 32. So max host we will connect = 30.

 Pratik said: (Wed, Jul 8, 2015 04:44:22 PM) Thanks @Nikhil but can you explain that binary conversions till 255?