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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. Use the formula (2^X) - 2 >= Y

  4. 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

  5. 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:

    https://networklessons.com/subnetting/variable-length-subnet-mask-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 thi

    ... Continue reading in our forum

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