Am I doing VLSM correctly?

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Here is a link to a practice exercise I found online:

http://www.informatikerin.hs-bremen.de/homepage/institutionen/Cisco13/ccnp/ccnp1/en_CCNP1_v30/PDF/lab_2_10_2c.pdf

I am just looking to make sure I am doing this correctly. Any feedback
is appreciated.

I start out with the block 192.168.24.0/22

I see my largest group of hosts is 400, which requires 9 bits
192.168.24.0/22 gets broken down into:
    192.168.24.0/23 (capable of 510 hosts)(used for the 400 hosts)
    192.168.26.0/23 (further subnetted below)

Now I need to get a block that can service 200 hosts (requires 8 bits)
192.168.26.0/23 gets broken down into:
    192.168.26.0/24 (capable of 254 hosts)(used for the 200 hosts)
    192.168.27.0/24 (further subnetted below)

Now I need two blocks that can service 50 hosts each (6 bits required)
To reduce waste, I broke this into a /25 to get the following:
    192.168.27.0/25 (126 hosts each) (further subnetted below)
    192.168.27.128/25

192.168.27.0/25 gets broken down further into:
    192.168.27.0/26 (capable of 62 hosts each)
    192.168.27.64/26 (capable of 62 hosts each
    (These two fill the need for both of the 50 hosts)

I have 192.168.27.128/25 left over to further subnet or use to address
more hosts.


Re: Am I doing VLSM correctly?
Looks good to me Chad..  You used the exact same method that I learned
while studying for my Cisco certs.  Start with the largest number of
hosts and break it down from there.

Phillip

Chad wrote:
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http://www.informatikerin.hs-bremen.de/homepage/institutionen/Cisco13/ccnp/ccnp1/en_CCNP1_v30/PDF/lab_2_10_2c.pdf
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Re: Am I doing VLSM correctly?
the network is 192.168.24.0. The first byte, 192 tells us that this is
a class c network, therefore the minimum subnet should be 255.255.255.0
or the default subnet mask for c if you are doing it classful.

Therefore based on the minimum subnets for a class c network and the
fact that  every subnet should have at least 2 bits for the network
Ids, the maximum hosts you can get on a class c network is 2 raised to
6 minus 2 which is a /26 mask and with at most 62 hosts. There is no
way you can implement a class c network for 400 or 200 hosts without
making the configuration fitting for a class A or class B network, that
is why corporations start with a class a because they believe that with
time the network would surely get larger and more hosts would be needed
for a subnet.

CIDR just won't work on 400 or 200 hosts with the given network
address.
pmccollum@DONTSPAMMEgeemail.com wrote:
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