Hi,

I was asked as an exercise to divide up an internal network utilizing
10.0.0.0/8 into 16 different networks. Can someone please review the
few that I've listed below for accuracy? Also, would I be correct in
that there are 24 host bits in each network?

Thanks,
James


#1
Subnet Mask Subnet Size
172.16.0.0 255.255.240.0 4094

Host Range Broadcast
172.16.0.1 to 172.16.15.254 172.16.15.255

#2
Subnet Mask Subnet Size
172.16.16.0 255.255.240.0 4094

Host Range Broadcast
172.16.16.1 to 172.16.31.254 172.16.31.255

#3
Subnet Mask Subnet Size
172.16.32.0 255.255.240.0 4094

Host Range Broadcast
172.16.32.1 to 172.16.47.254 172.16.47.255

In article <1149650529.505831.9220@g10g2000cwb.googlegroups.c om>,
<v8killah03@yahoo.com> wrote:
>I was asked as an exercise to divide up an internal network utilizing
>10.0.0.0/8 into 16 different networks.

Was it specified as 10.0.0.0/8 or as 10.0.0.0 with a netmask of 255.0.0.0 ?
If it was specified in terms of the netmask instead of /8 then it
was a trick question; google for "ip subnet-zero" to see why.

>Can someone please review the
>few that I've listed below for accuracy?

>#1
>Subnet Mask Subnet Size
>172.16.0.0 255.255.240.0 4094

Potentially not valid; cf. the subnet-zero reference.


>Also, would I be correct in
>that there are 24 host bits in each network?

No. Count the number of leading binary 1's in 255.255.240.0 .

In article <1149650529.505831.9220@g10g2000cwb.googlegroups.c om>,
v8killah03@yahoo.com wrote:

> Hi,
>
> I was asked as an exercise to divide up an internal network utilizing
> 10.0.0.0/8 into 16 different networks. Can someone please review the
> few that I've listed below for accuracy? Also, would I be correct in
> that there are 24 host bits in each network?

If you were asked to break up 10.0.0.0/8, why do all the networks in
your response start with 172.16? They should be 10.x.x.x.

>
> Thanks,
> James
>
>
> #1
> Subnet Mask Subnet Size
> 172.16.0.0 255.255.240.0 4094
>
> Host Range Broadcast
> 172.16.0.1 to 172.16.15.254 172.16.15.255
>
> #2
> Subnet Mask Subnet Size
> 172.16.16.0 255.255.240.0 4094
>
> Host Range Broadcast
> 172.16.16.1 to 172.16.31.254 172.16.31.255
>
> #3
> Subnet Mask Subnet Size
> 172.16.32.0 255.255.240.0 4094
>
> Host Range Broadcast
> 172.16.32.1 to 172.16.47.254 172.16.47.255

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

I was going off an example that I found. So, should I change all
values of 172.16... to 10.16...., effectively replacing all values 172
to 10?

Also, regarding a previous reply to my message, it was stated as
10.0.0.0/8.

Thanks a lot!!

James


Barry Margolin wrote:
> In article <1149650529.505831.9220@g10g2000cwb.googlegroups.c om>,
> v8killah03@yahoo.com wrote:
>
> > Hi,
> >
> > I was asked as an exercise to divide up an internal network utilizing
> > 10.0.0.0/8 into 16 different networks. Can someone please review the
> > few that I've listed below for accuracy? Also, would I be correct in
> > that there are 24 host bits in each network?
>
> If you were asked to break up 10.0.0.0/8, why do all the networks in
> your response start with 172.16? They should be 10.x.x.x.
>
> >
> > Thanks,
> > James
> >
> >
> > #1
> > Subnet Mask Subnet Size
> > 172.16.0.0 255.255.240.0 4094
> >
> > Host Range Broadcast
> > 172.16.0.1 to 172.16.15.254 172.16.15.255
> >
> > #2
> > Subnet Mask Subnet Size
> > 172.16.16.0 255.255.240.0 4094
> >
> > Host Range Broadcast
> > 172.16.16.1 to 172.16.31.254 172.16.31.255
> >
> > #3
> > Subnet Mask Subnet Size
> > 172.16.32.0 255.255.240.0 4094
> >
> > Host Range Broadcast
> > 172.16.32.1 to 172.16.47.254 172.16.47.255
>
> --
> Barry Margolin, barmar@alum.mit.edu
> Arlington, MA
> *** PLEASE post questions in newsgroups, not directly to me ***
> *** PLEASE don't copy me on replies, I'll read them in the group ***

In article <1149684598.478740.142770@y43g2000cwc.googlegroups .com>,
v8killah03@yahoo.com wrote:

> I was going off an example that I found. So, should I change all
> values of 172.16... to 10.16...., effectively replacing all values 172
> to 10?

Yes. Otherwise you're not dividing up the same network you were told to
divide up.

But this also changed the rest of the answer, like the appropriate
subnet mask to use. Your answer was correct if you were asked to divide
up a /16, not a /8.

>
> Also, regarding a previous reply to my message, it was stated as
> 10.0.0.0/8.
>
> Thanks a lot!!
>
> James
>
>
> Barry Margolin wrote:
> > In article <1149650529.505831.9220@g10g2000cwb.googlegroups.c om>,
> > v8killah03@yahoo.com wrote:
> >
> > > Hi,
> > >
> > > I was asked as an exercise to divide up an internal network utilizing
> > > 10.0.0.0/8 into 16 different networks. Can someone please review the
> > > few that I've listed below for accuracy? Also, would I be correct in
> > > that there are 24 host bits in each network?
> >
> > If you were asked to break up 10.0.0.0/8, why do all the networks in
> > your response start with 172.16? They should be 10.x.x.x.
> >
> > >
> > > Thanks,
> > > James
> > >
> > >
> > > #1
> > > Subnet Mask Subnet Size
> > > 172.16.0.0 255.255.240.0 4094
> > >
> > > Host Range Broadcast
> > > 172.16.0.1 to 172.16.15.254 172.16.15.255
> > >
> > > #2
> > > Subnet Mask Subnet Size
> > > 172.16.16.0 255.255.240.0 4094
> > >
> > > Host Range Broadcast
> > > 172.16.16.1 to 172.16.31.254 172.16.31.255
> > >
> > > #3
> > > Subnet Mask Subnet Size
> > > 172.16.32.0 255.255.240.0 4094
> > >
> > > Host Range Broadcast
> > > 172.16.32.1 to 172.16.47.254 172.16.47.255
> >
> > --
> > Barry Margolin, barmar@alum.mit.edu
> > Arlington, MA
> > *** PLEASE post questions in newsgroups, not directly to me ***
> > *** PLEASE don't copy me on replies, I'll read them in the group ***

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***

In article <barmar-853136.08554907062006@comcast.dca.giganews.com>,
Barry Margolin <barmar@alum.mit.edu> wrote:

>But this also changed the rest of the answer, like the appropriate
>subnet mask to use. Your answer was correct if you were asked to divide
>up a /16, not a /8.

The question as stated did not require that the 16 subnetworks
together cover the original network; nor that the 16 subnetworks were
each the same size. For example, the question as stated could
have been solved with one each of a /9 through /23 and two /24.

I think I get it now. So, something like this? Thanks again for the
btw.

#1
Subnet Mask Subnet Size
10.8.0.0 255.255.240.0 4094


Host Range Broadcast
10.16.0.1 to 10.8.7.254 10.8.7.255


#2
Subnet Mask Subnet Size
10.8.8.0 255.255.240.0 4094


Host Range Broadcast
10.8.8.1 to 10.8.15.254 10.8.15.255


#3
Subnet Mask Subnet Size
10.8.16.0 255.255.240.0 4094


Host Range Broadcast
10.8.16.1 to 10.8.23.254 10.8.23.255

Barry Margolin wrote:
> In article <1149684598.478740.142770@y43g2000cwc.googlegroups .com>,
> v8killah03@yahoo.com wrote:
>
> > I was going off an example that I found. So, should I change all
> > values of 172.16... to 10.16...., effectively replacing all values 172
> > to 10?
>
> Yes. Otherwise you're not dividing up the same network you were told to
> divide up.
>
> But this also changed the rest of the answer, like the appropriate
> subnet mask to use. Your answer was correct if you were asked to divide
> up a /16, not a /8.
>
> >
> > Also, regarding a previous reply to my message, it was stated as
> > 10.0.0.0/8.
> >
> > Thanks a lot!!
> >
> > James
> >
> >
> > Barry Margolin wrote:
> > > In article <1149650529.505831.9220@g10g2000cwb.googlegroups.c om>,
> > > v8killah03@yahoo.com wrote:
> > >
> > > > Hi,
> > > >
> > > > I was asked as an exercise to divide up an internal network utilizing
> > > > 10.0.0.0/8 into 16 different networks. Can someone please review the
> > > > few that I've listed below for accuracy? Also, would I be correct in
> > > > that there are 24 host bits in each network?
> > >
> > > If you were asked to break up 10.0.0.0/8, why do all the networks in
> > > your response start with 172.16? They should be 10.x.x.x.
> > >
> > > >
> > > > Thanks,
> > > > James
> > > >
> > > >
> > > > #1
> > > > Subnet Mask Subnet Size
> > > > 172.16.0.0 255.255.240.0 4094
> > > >
> > > > Host Range Broadcast
> > > > 172.16.0.1 to 172.16.15.254 172.16.15.255
> > > >
> > > > #2
> > > > Subnet Mask Subnet Size
> > > > 172.16.16.0 255.255.240.0 4094
> > > >
> > > > Host Range Broadcast
> > > > 172.16.16.1 to 172.16.31.254 172.16.31.255
> > > >
> > > > #3
> > > > Subnet Mask Subnet Size
> > > > 172.16.32.0 255.255.240.0 4094
> > > >
> > > > Host Range Broadcast
> > > > 172.16.32.1 to 172.16.47.254 172.16.47.255
> > >
> > > --
> > > Barry Margolin, barmar@alum.mit.edu
> > > Arlington, MA
> > > *** PLEASE post questions in newsgroups, not directly to me ***
> > > *** PLEASE don't copy me on replies, I'll read them in the group ***
>
> --
> Barry Margolin, barmar@alum.mit.edu
> Arlington, MA
> *** PLEASE post questions in newsgroups, not directly to me ***
> *** PLEASE don't copy me on replies, I'll read them in the group ***

Think binary:
Mask:
11111111.00000000.00000000.00000000
IPs
00001010.xxxxxxxx.00000000.00000000

The x's is what you have to divide, and you want to make that
difference as large as you want, then you start moving your most
significant bits until you fix your problem:

xxxxxxxx:
0000 0000 = 0
0001 0000 = 16
0010 0000 = 32
0011 0000 = 48
0100 0000 = 64
0101 0000 = ...
0110 0000
0111 0000
1000 0000
1001 0000
1010 0000
1011 0000
1100 0000
1101 0000
1110 0000
1111 0000


v8killah03@yahoo.com wrote:
> I think I get it now. So, something like this? Thanks again for the
> btw.
>
> #1
> Subnet Mask Subnet Size
> 10.8.0.0 255.255.240.0 4094
>
>
> Host Range Broadcast
> 10.16.0.1 to 10.8.7.254 10.8.7.255
>
>
> #2
> Subnet Mask Subnet Size
> 10.8.8.0 255.255.240.0 4094
>
>
> Host Range Broadcast
> 10.8.8.1 to 10.8.15.254 10.8.15.255
>
>
> #3
> Subnet Mask Subnet Size
> 10.8.16.0 255.255.240.0 4094
>
>
> Host Range Broadcast
> 10.8.16.1 to 10.8.23.254 10.8.23.255
>
> Barry Margolin wrote:
> > In article <1149684598.478740.142770@y43g2000cwc.googlegroups .com>,
> > v8killah03@yahoo.com wrote:
> >
> > > I was going off an example that I found. So, should I change all
> > > values of 172.16... to 10.16...., effectively replacing all values 172
> > > to 10?
> >
> > Yes. Otherwise you're not dividing up the same network you were told to
> > divide up.
> >
> > But this also changed the rest of the answer, like the appropriate
> > subnet mask to use. Your answer was correct if you were asked to divide
> > up a /16, not a /8.
> >
> > >
> > > Also, regarding a previous reply to my message, it was stated as
> > > 10.0.0.0/8.
> > >
> > > Thanks a lot!!
> > >
> > > James
> > >
> > >
> > > Barry Margolin wrote:
> > > > In article <1149650529.505831.9220@g10g2000cwb.googlegroups.c om>,
> > > > v8killah03@yahoo.com wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > I was asked as an exercise to divide up an internal network utilizing
> > > > > 10.0.0.0/8 into 16 different networks. Can someone please review the
> > > > > few that I've listed below for accuracy? Also, would I be correct in
> > > > > that there are 24 host bits in each network?
> > > >
> > > > If you were asked to break up 10.0.0.0/8, why do all the networks in
> > > > your response start with 172.16? They should be 10.x.x.x.
> > > >
> > > > >
> > > > > Thanks,
> > > > > James
> > > > >
> > > > >
> > > > > #1
> > > > > Subnet Mask Subnet Size
> > > > > 172.16.0.0 255.255.240.0 4094
> > > > >
> > > > > Host Range Broadcast
> > > > > 172.16.0.1 to 172.16.15.254 172.16.15.255
> > > > >
> > > > > #2
> > > > > Subnet Mask Subnet Size
> > > > > 172.16.16.0 255.255.240.0 4094
> > > > >
> > > > > Host Range Broadcast
> > > > > 172.16.16.1 to 172.16.31.254 172.16.31.255
> > > > >
> > > > > #3
> > > > > Subnet Mask Subnet Size
> > > > > 172.16.32.0 255.255.240.0 4094
> > > > >
> > > > > Host Range Broadcast
> > > > > 172.16.32.1 to 172.16.47.254 172.16.47.255
> > > >
> > > > --
> > > > Barry Margolin, barmar@alum.mit.edu
> > > > Arlington, MA
> > > > *** PLEASE post questions in newsgroups, not directly to me ***
> > > > *** PLEASE don't copy me on replies, I'll read them in the group ***
> >
> > --
> > Barry Margolin, barmar@alum.mit.edu
> > Arlington, MA
> > *** PLEASE post questions in newsgroups, not directly to me ***
> > *** PLEASE don't copy me on replies, I'll read them in the group ***