Question

What is the first valid host on the subnetwork?

Answer 1

While you should definitely know how to figure this in binary, I use little tricks in the real world instead. For this type of thing I like to use the number 256.

Here's what I think is the "easiest"

Find the "interesting" octet of the subnet mask. In this case it is the 3rd octet because that's where the network bits and the host bits meet. Now subtract that number from 256.

256-254=2

This tells you that the ALL networks with 255.255.254.0 subnet mask will have addresses that are multiples of 2. Like this:

172.29.0.0

172.29.2.0

172.29.4.0

172.29.6.0

...

172.29.254.0

172.30.0.0

With that information, you know that the 3rd octet in the network address has to be a multiple of 2 so find the closest multiple that occurs before 151. The next network will be at the next multiple of 2.

That gives you your network address and the next network address very quickly which is all you need.

Network: 172.29.150.0

First address: 172.29.150.1

Last address: 172.29.151.254

Broadcast: 172.29.151.255

Next network: 172.29.152.0

All that just by subtracting from 256. I made user of this back when I took my icnd1 and realized I barely used my chart, if at all. Hope