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TOPIC: subnet calculation

subnet calculation 14 years 1 month ago #6401

  • apit
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i'm a little bit confuse about subnet calculation..
as i know, class A begin with 1.x.x.x - 126.x.x.x,class B begin with 128.0.x.x - 192.255.x.x and class C begin with 192.0.0.x - 223.255.255.x
at my office, they use 10.20.x.x ip with netmask..
10.20.x.x is class A range but is class B netmask..
is it valid?or is it my missunderstand about ip calculation..

Re: subnet calculation 14 years 1 month ago #6402

Hello apit, i think you are a bit confused about subnetting. My advise is that you study about ip subnetting and in the beginning you can use a subnet calculator to help you out. Solarwinds offers a subnet calculator for free and it is a good one, visit .
Now for the given subnet, yes it is valid, it is a Class A address subnetted with 1022 hosts per subnet (correct me if I'm wrong but i'm steel sleepy :? ). Hope i helped......

Re: subnet calculation 14 years 1 month ago #6403

You're subnetting a Class A private address space with a class C subnet mask.. its perfectly legal. These days everything is classless anyway.

Sahir Hidayatullah. Staff - Associate Editor & Security Advisor
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