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TOPIC: IP addressing

IP addressing 13 years 5 months ago #407

  • mydeuter
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let say if ip network is (202.185.164.0/20)..is it true that this ip network has 2^4-2 = 14 network and 2^12-2 = 4094 hosts ? TQ
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IP addressing 13 years 5 months ago #408

  • Chris
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Deuter,

A Network of 202.185.164.0 / 20 would give you 2^12-2= valid 4094 hosts and 2^(8+4)-2= 4094 networks, thought you could also use the 2 networks we subtracked in the equasion which would give you 4096 networks.

I think you got mixed up with the subnet bits as you counted 4 subnet bitspossibly because you saw the network as a Default Class C network, where as its 8(default class C)+4 which is a total of 12.

To confirm this number all you simply need to do is the following: The /20 means 20 subnetmask bits from a total of 32, therefore, 32-20=12 This is the number you need to put in the power of 2 in order to find out your networks.

Hope this helps resolve your question !

Cheers,
Chris Partsenidis.
Founder & Editor-in-Chief
www.Firewall.cx
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IP addressing 13 years 4 months ago #409

  • mcse_nair
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Chris i have a small doubt in this...
202.X.X.X is a class c address, by default with which u can get 255 host ids. Now when u give a mask of 20(i.e 255.255.240.0), then does the 3rd octet account for both the host ids and network ids.

plz explian this to me.

thanks.
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Re: IP addressing 13 years 4 days ago #642

  • kavita
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Folks,

First of all let us looking at the first octet in the ip address it is a class C address & so should have 8 host bits meaning 2^8-2 hosts ignoring the first & the last address.

Andy,

I am not sure if your question as such is based on Class C network or on CIDR (Classless Inter Domain Routing) addresses which are normally written in the /20 or /x format & has no specific classed defined.

In simple language when u say 202.185.164.0/20 means the first 20 bits are for network & the remaining 12 bits are for hosts.

Further analyzing the above address basically the network portion would be defined as 202.185.160.0 network & would have hosts starting with 202.185.160.1 to 202.185.160.254

Please confirm what exactly are u talking abt if not CIDR then we should have a proper class C address with the right subnet mask.
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