Re: Subnetting Question


"RogueIT" <RogueIT@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:85972EE5-6CCB-4C3D-A16C-9FFF36844F47@xxxxxxxxxxxxxxxx
I just got done working a practice question and I understand the subnet
part...I don't get how the IP address answers are figured. Below is the
question is someone could tell me why address x is good for network y
thanks,
Rogue
****************************************************
You administer a network that contains 175 machines. Your manager has
assigned the network
the IP address 192.168.11.0 with the default subnet mask of 255.255.255.0. A
router that has
one WAN interface and eight LAN interfaces connects this network to the
corporate WAN.
You want to subnet the network into three subnets, and you want to reserve a
few addresses for
a fourth subnet, just in case you need it later. You decide that Subnet A
will contain 25 computers,
Subnet B will contain 50 computers, and Subnet C will contain 100 computers.
In the following exhibit, select the network addresses and subnet masks in
the Choices column and
place them in the appropriate boxes in the other three columns. Each item
may be used only once.
Choices:
192.168.11.128
255.255.255.128
192.168.11.0
255.255.255.192
192.168.11.192
255.255.255.224

Network A Network B Network C
IP Address __________ _________ ________
Subnet __________ _________ ________

The network address 192.168.11.192 with a subnet mask of 255.255.255.224 is
perfect for
Subnet A because it supports up to 30 hosts. The network address
192.168.11.128 with a subnet
mask of 255.255.255.192 is perfect for Subnet B because it supports up to 62
hosts. The network
address 192.168.11.0 with a subnet mask of 255.255.255.128 is perfect for
Subnet C
because it supports up to 126 hosts. That still leaves the network address
192.168.11.224 with
a subnet mask of 255.255.255.224 available for a fourth subnet later.


Note: the question (or your quoting of it) has an inherent error in it as the 192.168.11.128 network will conflict with the other two networks. The question should have been...

Choices:
192.168.11.0 - 255.255.255.128
192.168.11.128 - 255.255.255.192
192.168.11.192 - 255.255.255.224
leaving 192.168.11.224 - 255.255.255.224

Given the corrected question...
You are given three subnets and asked which network should use which subnet. One subnet (192.168.11.0) can support up to 126 hosts, one subnet (192.168.11.128) can support up to 62 hosts, and one subnet (192.168.11.192) can support up to 30 hosts. The requirement is that you need 100, 50, and 25 hosts on each subnet. Simply plug and play. You can't put the 100 hosts or the 50 hosts on the subnet that only supports 30 hosts.

To find how many hosts a subnet will support, look at the subnet mask. In the first example 255.255.255.128, the first 25 bits are for the network ID, and this leaves 7 bits for the host id. Take the number 2, raise it to the 7th power, and then subtract one for the network Id and one for the broadcast id, this leaves 126.

John R

.

Relevant Pages

  • Calculating subnet hosts
    ... Your company has been assigned a network ID of 197.132.240.0. ... The max number of hosts per subnet is 25. ... Class A addresses have the highest level bit turned ...
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  • Re: IP Address problems
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  • Re: Can I use swticher instead of router in this case?
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    (microsoft.public.cert.exam.mcse)
  • Re: ICS questions and confusion
    ... >>>It doesn't HAVE to be on a different subnet, ... but that requires that the ICS host become a bridge. ... >> ICS is a software based NAT router, and routers work best when the ... >> network already had the required address 192.168.0.1" is confusing. ...
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