help figuring out CIDR notation

I have a network address of 136.15.224.0.
I have a max number of hosts of 100
i would need a host bits of 7
the largest subnet is 100, so it would require 7 host_id bits
number of subnets is 10
number of subnet_id bits needed is 4
the supernet is /21

the subnet mask works out to be /25.

which would i use for the CIDR? I am confused here, I have chosen /21 so far, as I have a network of 3 subnetworks, but I have to increment by 1 as 3 doesn't work, so I have chosen 4 subnet bits needed.

I am made a table of the subnetworks and their IP ranges (there would be 1 unused).

With the /25 CIDR, I cannot split the network into 4. it doesn't seem to compute, so the only other answer is /21.

Is this correct

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Comments

advanex1

Maybe my old brain is confused, but are you trying to summarize routes? You're asking about trying to figure out a CIDR while also mentioning supernets.

Was the subnet mask for 136.15.224.0 not already given? Are you trying to determine what subnet mask/CIDR allows for a maximum of 100 hosts? I guess I'm just kind of confused on what you're asking.

kyle01

advanex1 wrote: »

Maybe my old brain is confused, but are you trying to summarize routes? You're asking about trying to figure out a CIDR while also mentioning supernets.

Was the subnet mask for 136.15.224.0 not already given? Are you trying to determine what subnet mask/CIDR allows for a maximum of 100 hosts? I guess I'm just kind of confused on what you're asking.

All I am given is the network address, I also given the following information:

1. using fixed-length sub-net mask
2. subnetwork 1 = 1 router (100 hosts), subnetwork 2 = 4 routers (router 1 = 12 hosts, router 2 = 75 hosts, router 3 = 16 hosts and router 4 = 10 hosts).

The diagram thus contains, 7 LANs 1 Backbone and 2 Leased Lines.

I am struggling to find the correct subnet mask with CIDR.

pinkiaiii

im practising subnets and are you sure the questions isnt asking you to create subnets with following paramaters one for 100hosts,2 for 75 which is a bit odd,then 3 for 16 hosts and 4 for 10 ?

thus you could basically work with class c mask on that.

or either some sort of trick question thus you could use class b cidr of /25 giving you 512 subnets and 128 hosts per subnet,but i dont believe question is written out correctly,since it would amount to huge wastage of networks.