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Subnets/Hosts Question

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corgus Joined: 14 Feb 2005 Posts: 1	Posted: Mon Feb 14, 2005 2:52 am    Post subject: Subnets/Hosts Question Trying to figure out how to come up with the valid subnet masks available if given a Class B address that will be split into 300 subnets with 45 max hosts on each subnet. Any assistance in helping me to understand this concept would be much appreciated.
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myk3 Joined: 18 Feb 2005 Posts: 15	Posted: Fri Feb 18, 2005 9:54 am    Post subject: Re: Subnets/Hosts Question corgus wrote: Trying to figure out how to come up with the valid subnet masks available if given a Class B address that will be split into 300 subnets with 45 max hosts on each subnet. Any assistance in helping me to understand this concept would be much appreciated. you are using a class b address, the default subnetmask for that is 255.255.0.0, you want to make a subnet so you can have a min of 300 subnets with a max of 45 hosts per subnet. so you need to borrow bits from the host part of the ip. to work this out do this count up from 2 doubling the number each time like this until you get to above 300, 2,4,8,16,32,64,128,256,512 so you have borrowed 9 bits of the host so add 9 bits on to the default subnetmask: 11111111.11111111.11111111.10000000, in decimal this is 255.255.255.192. this will give you 512 subnets each with 128 hosts per subnet. its all very easy when ya get used to it hth myk3
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