Thanks for the info, I was afraid that was the case.

I hope your holiday good.

Kim

From: Reimer, Mark [mailto:[email protected]]
Sent: Friday, May 25, 2012 4:16 PM
To: NT System Admin Issues
Subject: RE: subnetting question

Yes. For a /22 mask, you need to be on a 4,8,12... boundary. As in your subnets 
below, the /23 all start with an even number and include the next number 
(16-17, 18-19, etc)

As you probably know, masks are based on binary math. I can't quickly find a 
tutorial for this, but many exist, as do subnet calculators.

For you Americans, have a great long weekend. Us Canucks had ours last weekend.

Mark

From: Kim Longenbaugh [mailto:[email protected]]
Sent: Friday, May 25, 2012 2:58 PM
To: NT System Admin Issues
Subject: subnetting question

I must not understand all I know about subnetting....

Here's the deal:
I started out with these two subnets (I'm including the subnet and broadcast 
addresses):
172.16.8.0/22 = 172.16.8.0-172.16.11.255
172.16.12.0/22 = 172.16.12.0-172.16.15.255

I planned to segment my campus, so I planned to use the following subnets, 
which I wanted to have 512 addresses instead of 1024:
172.16.16.0-172.16.17.255/23       not in use yet
172.16.18.0-172.16.19.255/23       not in use yet
172.16.20.0-172.16.21.255/23       not in use yet
172.16.22.1-172.16.23.254/23       in use, working ok
172.16.24.1-172.16.25.254/23       not in use yet

However, when I tried to use this subnet, with a /22 for 1024 addresses, my 
router doesn't like it, and when creating a DHCP scope, it tries to make a 
superscope.
172.16.26.0/22 = 172.16.26.0-172.16.29.255

It seems to me I should be able to do what I've described, but apparently I'm 
misunderstanding things.
So one question is, why can't I do what I've outlined?

Another way to put it is, if I want a /22 subnet, I still have to make them on 
the 4,8,12,16,20,24,28..... boundaries?


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