well lets see if he`s right .....boys and girls.....
first how do we calculate the sum
the ip address is 172.108.168.0
this is a class B address which would mean that in our question the last
digit is not important.
next it has "/21" which indicates a subnet mask of 21 bits...in a standard
ip address we have 32 bits 11111111.11111111.11111111.11111111
which is represented as 255.255.255.255 in DECIMAL
"/21" would indicate that the subnet mask is
11111111.11111111.11111000.00000000
as we are not concerned with the last digits (its a class b address which
will use the last digit as host address) the subnet mask is actually
11111111.11111111.11111000.
first ignore the fist two sets of digits as these are not part of our
PRESENT CALCULATION
next take the last 11111000 and calculate like this
11111 is for the network 000 is for the hosts
the 8 bits map to a numbering system like this
1. 1. 1. 1. 1. 1. 1. 1
128 64 32 16 8 4 2 1
so 11111000 would work out as 128+64+32+16=248
next is easy 248 -256 =8 that is the number gap beetween your subnets!!!
so not starting at 0 and not ending at 255 (reserved and broadcast)
lets count
172.108.8.0
172.108.16.0
172.108.24.0
172.108.32.0
""""""""""""
172.108.168.0
172.108.172.0
so as one address in any subnet must be the broadcast address for that
subnet you can see
172.108.168.1 to 172.108.172.254
that is 2046 hosts in 30 subnets
alternitively you could just download
the ip calculator form 3netgroup site and it will tell you all this
LAST SUBNETTING QUESTION PLEASE........WE SHOULD HAVE HAVE GOT THIS IN
NETWORK ESSENTIALS ON YOUR MCSE
regards
steve
>From: Justin Marcus <[EMAIL PROTECTED]>
>Reply-To: Justin Marcus <[EMAIL PROTECTED]>
>To: jeongwoo park <[EMAIL PROTECTED]>
>CC: [EMAIL PROTECTED]
>Subject: Re: VLSM Question
>Date: Fri, 16 Jun 2000 20:00:02 +1000 (EST)
>
>hey im just learning about vlsm, so theres a good chance this is wrong :)
>anyways i'd say
>172.108.168.0
>x.x.169.0
>x.x.170.0
>x.x.171.0
>x.x.172.0
>x.x.173.0
>x.x.174.0
>x.x.175.0
>
>Justin...
>
>
>On Thu, 15 Jun 2000, jeongwoo park wrote:
>
> > I have a guestion regarding VLSM
> > How many subnet addresses can be summarized by 172.108.168.0/21?
> > how could you calculate it?
> > thanks in advance.
> >
> > ........................................................
> > iWon.com http://www.iwon.com why wouldn't you?
> > ........................................................
> >
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