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## Forum Replies

1. Hi Rene
When creating this blocks, do they have to be of equal size?

For example, you have an address of 10.10.10.0/23, and I am working to create a network/mask for the below requirements

I. 24 hosts
II. 111 hosts
III. 47 hosts
IV. 200 hosts

I came up with this , can you let me know if this is correct

I. 10.10.10.0/27
II. 10.10.10.128/25
III. 10.10.10.64/26
IV. 10.10.11.0/24

If I did this way, is this correct?

I. 10.10.10.192/27
II. 10.10.11.64/25
III. 10.10.11.0/26
IV. 10.10.10.0/24

Thanks
Palani

2. Palani,
Short answer: Everything you have is correct. For any given subnet mask, the block size is always the same.

People do subnetting many different ways. I haven’t heard of others doing it my way, but it works for me. I thought I might share with you how I can do subnetting very fast in my head–no calculators or even pencil and paper required.

I use the formula 2^X >= Y, which reads as 2 to the Xth power is greater than or equal to Y. Y is the number of hosts (or subnets) you are trying to figure out, and X is the variable you are trying to solve for.

... Continue reading in our forum

3. Guys, I need help. Every time I try getting into different topics, be it NAT, Routing Policy, etc - I always get back to Subnetting. I finally realized there’s no way to progress without mastering this subject. I google everywhere, but I need your help and hopefully I’ll finally figure this out. Please, show me how would you answer this question;

Write a standard ACL that will cover the host range from 192.168.100.128 through 192.168.100.131.

Let’s not worry about the ACL part, but how would you go about writing an IP address with a subnet (wildcard) mask tha

... Continue reading in our forum

4. Hi Maros,

Once you understand the fundamentals of subnetting, a quick way to solve a question like this is to visualize it and think in “blocks”:

https://networklessons.com/subnetting/subnetting-in-decimal-fast-way/

And take a look at VLSM:

We want an access-list that matches four addresses, it starts with 192.168.100.128:

• 192.168.100.128
• 192.168.100.129
• 192.168.100.130
• 192.168.100.131

The first thing we need to figure out is what these addresses are. Is it an exact subnet? In this case

... Continue reading in our forum

5. Hello Ajeet

If you are originally given a range of 192.168.1.0/24, and you begin dividing it into smaller subnets, the first subnet is always the lowest. So if we begin dividing

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