I can subnet and im going for my CCENT exam Aug 20 and im a little stuck on this question, can someone show me in a really easy way on how the answer is got. I know the answer is but how?:

What is the last Usable host address on the third subnet for the following address and mask combination -

5 Years
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Last Post by JorgeM

So first, with a /29 (, you get 32 subnets from the subnet. Some routers will not allow the use of the first or last subnet. Most modern systems do.

The IP of falls within the 3 subnet: In each subnet you have 8 IPs.

The first IP is the network ID:
The last IP is the broadcast address for that subnet:

This leaves you with 6 usable IPs for your host: 17-22.

For you to be able to figure this out without using a subnet calculator, you need to have some experience working with binary (Base2) numbers.

Here are some resources you can use:

Tool | IP Subnet Calculator
Guide | CIDR and Subnetting


great...when it comes to binary, sometimes when you have free time, its a good idea to go through a few sample problems just to keep the concept fresh.

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