IPv4 subnetting problem.

[KaizenTech]

I'm learning computer networking through online tutorials and courses. I stumbled this problem which I'm not sure if my answer is correct or not. Maybe you guys could check or see if I got the right answer.

Here's the problem:

CBY corporation has 3 offices settled in three different cities. You have one class C network address, which you have divided evenly among the sites. Each site has no more than five managers and six supervisors, however the corporation's growth may require to support for up to 25 users per site.Additionaly CBY corporation plans to expand to two more cities in the next six months. Which subnet mask should you assign to users per site? List the first five available subnet IDs and host ranges.

Here's how I approached the problem:
First thing I did was, I wrote the givens of the problem

1. Corporation: CBY
2. Number of Offices: 3
3. IP add: 1 class of C network address
4. Offices (site) condition: 5 Managers and 6 Supervisors and may require up to 25 users per site.

The way I understood the problem (Please check if my understanding is right), was that the corporation had given the task to build their network using Class C IP addresses. So with the maximum users which is 25 users per site.

So, I formulated an IP which is 192.168.10.0, having the hosts which is minus 2. I got these IP ranges.

192.168.10.0 - 192.168.10.26
192.168.10.27 - 192.168.10.52
192.168.10.53 - 192.168.10.78
192.168.10.79 - 192.168.10.104
192.168.10.105 - 192.168.10.130

I added +1 to the number of maximum users which is 25, and with +1 = 26, because the first and last host addresses is unusable.

Thus my answer correct or not? Need your help.

 

[Kaktussoft]

since subnets work with bitmasks like 255.255.255.192, 26 computers is impossible
255.255.255.192 means 11111111.11111111.11111111.11000000

6 zero's so 2^6=64 differents addresses.
255.255.255.224 means 11111111.11111111.11111111.11100000
5 zero's so 2^5 different addresses. so 32 addresses

You have to extract 2 but that you know already. So 30 computers can have an unique tcpipv4 address with subnet mask 255.255.255.224

192.168.10.0/255.255.255.224
192.168.10.32/255.255.255.224
192.168.10.64/255.255.255.224
192.168.10.96/255.255.255.224
192.168.10.128/255.255.255.224
192.168.10.160/255.255.255.224
192.168.10.192/255.255.255.224
192.168.10.224/255.255.255.224

Now you created 8 subnets of 32 addresses each. 8*32=256 so easy to remember.