subnetting (helps security)

Discussion in 'Computer Security' started by new guy, May 18, 2006.

1. new guyGuest

I am studying subnetting and I have a few question, if you do not mind.

1. why will the network number be 0 if we borrow just 1 bit?

2. is my table correct?
Usable Sub/Hosts (Total S/hosts - 2)

62
30
14
6
2

Total Sub/ hosts (256 - Sub/mask)

64
32
16
8
4

192
224
240
248
252

Bits Values
128
64
32
16
8
4
2
1

Borrowed bits Power

2
3
4
5
6

2
2
2
2
2

Total subnets

4
8
16
32
64

Usable subnets

2
6
14
30
62

3. why is the total number of subnet hosts the same as the last borrowed
bit's value?
4. why is the max number of subnets equal to the number 2 powered by the
number of the borrowed bits?
5. why do we use the ANDing method to find out if a certain IP address is
within a subnet?

new guy

new guy, May 18, 2006

2. new guyGuest

I am studying subnetting and I have a few question, if you do not mind.

1. why will the network number be 0 if we borrow just 1 bit?
2. is my table correct?

Usable Sub/Hosts(Total S/hosts - 2)

62
30
14
6
2

Total Sub/ hosts (256 - Sub/mask)

64
32
16
8
4

128
192
224
240
248
252
254
255

Bits Values
128
64
32
16
8
4
2
1

Borrowed bits Power

2
3
4
5
6

2
2
2
2
2

Total subnets

4
8
16
32
64

Usable subnets

2
6
14
30
62

3. why is the total number of subnet hosts the same as the last borrowed bit's value?
4. why is the max number of subnets equal to the number 2 powered by the number of the borrowed bits?
5. why do we use the ANDing method to find out if a certain IP address is within a subnet?

new guy

Sorry, I have to send the table in rich text format ....

new guy, May 18, 2006

3. Borked Pseudo MailedGuest

new guy wrote:

> I am studying subnetting and I have a few question, if you do not mind.

<snip>

Will we get paid for doing your homework?

Borked Pseudo Mailed, May 18, 2006
4. new guyGuest

Sure, That's a fair question, however, the table shows that I am working on
my homework. and you do not have to answer
"Borked Pseudo Mailed" <> wrote in message
news:...
> new guy wrote:
>
>> I am studying subnetting and I have a few question, if you do not mind.

>
> <snip>
>
> Will we get paid for doing your homework?

Sure, you can send me a bill. lol btw, isn't my table a homework
indication?
Anyway, I am looking only for short answers, not for details, kindly stating
"if you do not mind".

new guy

new guy, May 18, 2006
5. Borked Pseudo MailedGuest

new guy wrote:

> Sure, That's a fair question, however, the table shows that I am working
> on my homework. and you do not have to answer "Borked Pseudo Mailed"
> <> wrote in message
> news:...
>> new guy wrote:
>>
>>> I am studying subnetting and I have a few question, if you do not
>>> mind.

>>
>> <snip>
>>
>> Will we get paid for doing your homework?

>
> Sure, you can send me a bill. lol btw, isn't my table a homework
> indication?
> Anyway, I am looking only for short answers, not for details, kindly
> stating "if you do not mind".

The problem is most people DO mind doing your homework for you, even in
part, and you blatantly posted the entire assignment and asked us to just
fill it all in. You didn't even try and then come to us asking for
something you were having trouble with.

The assignment given to YOU for a reason. You're suppose to be learning
something in the process, even if it's just where to look for the
information if you need to refer back to it. Many of us have already been
through this process, done the work ourselves, and some of us even teach
others now.

Answering all your questions doesn't do you or anyone else any good at
all. No amount of sarcasm and adolescent "you don't have to answer"
bullshit will change that. If anything, it will considerably lower your
chances that anyone will be willing to bother replying at all. Let alone
do anything but spank you.

Why don't you try investing a little of your OWN time and effort first.
If you find you're just not up to the task you might make another attempt
to get help in a public forum, with something a little more genuine than
"Here's my worksheet, fill it out. Please". I'll bet you more people would

Or..... you could puff your chest out some more and reply like most kids
do in your situation, and get yourself labeled as a useless twit.

Either way makes absolutely no difference in MY life, because you're the
one with the problems that need answers. None of us have anything at all
to loose by not doing your work for you. We may even GAIN something down
the road by not doing it.

Borked Pseudo Mailed, May 19, 2006
6. new guyGuest

"Borked Pseudo Mailed" <> wrote in message
news:...
> new guy wrote:
>
>> Sure, That's a fair question, however, the table shows that I am working
>> on my homework. and you do not have to answer "Borked Pseudo Mailed"
>> <> wrote in message
>> news:...
>>> new guy wrote:
>>>
>>>> I am studying subnetting and I have a few question, if you do not
>>>> mind.
>>>
>>> <snip>
>>>
>>> Will we get paid for doing your homework?

>>
>> Sure, you can send me a bill. lol btw, isn't my table a homework
>> indication?
>> Anyway, I am looking only for short answers, not for details, kindly
>> stating "if you do not mind".

>
> The problem is most people DO mind doing your homework for you, even in
> part, and you blatantly posted the entire assignment and asked us to just
> fill it all in. You didn't even try and then come to us asking for
> something you were having trouble with.

>
> The assignment given to YOU for a reason. You're suppose to be learning
> something in the process, even if it's just where to look for the
> information if you need to refer back to it. Many of us have already been
> through this process, done the work ourselves, and some of us even teach
> others now.

Who is "us" ? Do you mean yourself ? Are you_the owner_of this forum?
I did not ask those questions to you personally, and from what I can see,
exchanging opinions are ways to learn, but arrogants like you try to
discourage people from learning this way just because you happened to learn
something by paying big bucks and spending a great deal of time. First time
that you attacked me, I tried to let it go, politely, but you seem to be an
annal.
Who are you to judge people if they ask right or wrong questions? Who told
you to read my posts in the first place, and why do you feel you have to
answer, no matter what ??? Do you know me, do you have any idea what I do
and why I am trying to get a better understanding of subnets? Why do you
assume (make an ass of yourself) that this is an assignment given to me?

>
> Answering all your questions doesn't do you or anyone else any good at
> all. No amount of sarcasm and adolescent "you don't have to answer"
> bullshit will change that.

Sarcasm and bullshit seem to be your best qualities, because your first
reaction was "Will we get paid for doing your homework?"

Nobody forces anybody to answer all, or part of questions, and you are
making a big mistake by teaching morals to people that do not ask for it!

If anything, it will considerably lower your
> chances that anyone will be willing to bother replying at all. Let alone
> do anything but spank you.

There are many nice, intelligent, helpful people in this forume, such as Mr.
Moe (old guy) and many others, so do not speak on behalf of the others. I
wish I could contact some of those people directly and, honestly, I wouldn't
mind even paying them for certain things!!!

>
> Why don't you try investing a little of your OWN time and effort first.
> If you find you're just not up to the task you might make another attempt
> to get help in a public forum, with something a little more genuine than
> "Here's my worksheet, fill it out. Please". I'll bet you more people would
> reply, and you'd find the answers a WHOLE lot more appealing.
>
> Or..... you could puff your chest out some more and reply like most kids
> do in your situation, and get yourself labeled as a useless twit.

I think this description fits your personality perfectly!

>
> Either way makes absolutely no difference in MY life, because you're the
> one with the problems that need answers. None of us have anything at all
> to loose by not doing your work for you. We may even GAIN something down
> the road by not doing it.
>

Get a life!

new guy, May 19, 2006
7. Borked Pseudo MailedGuest

new guy wrote:

>> The assignment given to YOU for a reason. You're suppose to be learning
>> something in the process, even if it's just where to look for the
>> information if you need to refer back to it. Many of us have already
>> been through this process, done the work ourselves, and some of us even
>> teach others now.

>
> Who is "us" ? Do you mean yourself ? Are you_the owner_of this forum? I

You see anyone else in a rush to do your work for you junior? Or even
defend your lazy, ignorant ass? That would tell anyone with an IQ larger
than their shoe size something.

I don't own this group, but I sure as **** own you.

> did not ask those questions to you personally, and from what I can see,
> exchanging opinions are ways to learn, but arrogants like you try to
> discourage people from learning this way just because you happened to

What a lying little Muppet you are. You weren't trying to LEARN anything,
you were trying to get everyone else to do your work for you. If that's
called "learning" In Canada it's no wonder they're third world.

> learn something by paying big bucks and spending a great deal of time.
> First time that you attacked me, I tried to let it go, politely, but you
> seem to be an annal.

You deserve every bit of ridicule that's heaped on you and more. The first
"attack" was highly restrained compared to the heaping pile of shit you
probably should have been served.

> Who are you to judge people if they ask right or wrong questions? Who

I'm the guy reading your lazy ass lying bullshit and shoving it back down

> told you to read my posts in the first place, and why do you feel you
> have to answer, no matter what ??? Do you know me, do you have any idea

WE know everything we NEED to know about you. You're a masturbatory
asshole who thinks people own him answers when he asks, and respect when
he doesn't deserve it. And you're a juvenile fukwit who stomps his feet
and screams like a little bitch when someone points that out.

If you had just a LICK of sense you you'd have let it go after the first
small jab to your ribs, but no.... here you are making yourself look like
a TOTAL ASSTARD by trying to defend your own laziness by acting like a
child.

Way to go, dimbulb.

> what I do and why I am trying to get a better understanding of subnets?
> Why do you assume (make an ass of yourself) that this is an assignment
> given to me?

You think I look like the ass here junior?

LOL!

Borrow a mirror and look for a clue.

>> Answering all your questions doesn't do you or anyone else any good at
>> all. No amount of sarcasm and adolescent "you don't have to answer"
>> bullshit will change that.

>
> Sarcasm and bullshit seem to be your best qualities, because your first
> reaction was "Will we get paid for doing your homework?"

That wasn't sarcasm.

> Nobody forces anybody to answer all, or part of questions, and you are
> making a big mistake by teaching morals to people that do not ask for
> it!

Just because you have no morals and admit it, doesn't mean you're immune
from having your amoral ass kicked from one end of Usenet to the other.

>
> If anything, it will considerably lower your
>> chances that anyone will be willing to bother replying at all. Let
>> alone do anything but spank you.

>
> There are many nice, intelligent, helpful people in this forume, such as
> Mr. Moe (old guy) and many others, so do not speak on behalf of the
> others. I wish I could contact some of those people directly and,
> honestly, I wouldn't mind even paying them for certain things!!!

nothing liar? If you wanted to pay someone you could have done it out in
the real world.

You're a lazy, lying asshole. From the top of your pointy head to the
bottoms of your stomping little feet.

> Get a life!

I have one. YOURS!

In fact I now grant you my permission to have the last word because I know
it's something you need to do to massage your battered sense of manhood
and bolster your shattered little ego.

Good day, looser.

Borked Pseudo Mailed, May 19, 2006
8. Sheik YurbhutiGuest

-----BEGIN PGP SIGNED MESSAGE-----
Hash: RIPEMD160

"new guy" <new ymous> wrote:

> Who is "us" ? Do you mean yourself ? Are you_the owner_of this forum?

<snip>

I don't know how much corroboration you'll require before you get the
point here, but I'll chime in by saying I don't particularly care for
the delivery, however the guy's message is dead nuts.

Your request was arrogant and presumptive. You did absolutely no work
on your own apparently, and yet you still seem to think that everyone
else has some moral obligation to give you all the answers, and only
the ones *you* want.

And yes, you're missing the entire point of doing homework. It's not
process and how you address problems on your own. That's something you
need to consider carefully.

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Sheik Yurbhuti, May 19, 2006
9. new guyGuest

"new guy" <new ymous> wrote in message
news:aP2bg.173153\$7a.104097@pd7tw1no...

I am studying subnetting and I have a few question, if you do not mind.

1. why will the network number be 0 if we borrow just 1 bit?

Ok, I guess I have to expand on my questions, but if you do not have
anything nice to say, please do not reply to my post at all.

I will take as an example the network address, 192.168.1.0 The default
The host addresses will be 192.168.1.1 up to 192.168.1. 254 where

If I borrow 1 bit (subnet mask 255.255.128.0) the result is:
126 usable hosts: 192.168.1.1 to 126; and 2 subnets as follows:
192.168.1.0 192.168.1.127
192.168.1.128 192.168.1.255

The ID of the first Subnetwork (0) is the same as the original network and
the broadcast ID of the second subnetwork (1) is the same as the broadcast
of the original network. However, I am missing something simple ( as it's
always the case and hoped somebody would give me at least a hint.

new guy

new guy, May 23, 2006
10. TwistyCreekGuest

new guy wrote:

>
> "new guy" <new ymous> wrote in message
> news:aP2bg.173153\$7a.104097@pd7tw1no...
>
> I am studying subnetting and I have a few question, if you do not mind.

Are we going to be paid for doing your homework?

TwistyCreek, May 23, 2006
11. new guyGuest

"new guy" <new ymous> wrote in message
news:tfucg.182438\$P01.40555@pd7tw3no...
>
> "new guy" <new ymous> wrote in message
> news:aP2bg.173153\$7a.104097@pd7tw1no...
>
> I am studying subnetting and I have a few question, if you do not mind.
>
> 1. why will the network number be 0 if we borrow just 1 bit?
>
> Ok, I guess I have to expand on my questions, but if you do not have
> anything nice to say, please do not reply to my post at all.
>
> I will take as an example the network address, 192.168.1.0 The default
> The host addresses will be 192.168.1.1 up to 192.168.1. 254 where
>
> If I borrow 1 bit (subnet mask 255.255.128.0) the result is:
> 126 usable hosts: 192.168.1.1 to 126; and 2 subnets as follows:
> 192.168.1.0 192.168.1.127
> 192.168.1.128 192.168.1.255
>
> The ID of the first Subnetwork (0) is the same as the original network and
> the broadcast ID of the second subnetwork (1) is the same as the broadcast
> of the original network. However, I am missing something simple ( as it's
> always the case and hoped somebody would give me at least a hint.
>
> new guy

Today, as I was having lunch, I figured out the answer to my first question.
Now, it's more obvious to me that such a simple question has nothing to do
with "doing my homework" as some jerk called it; it was an oversight and it
had to do with the way it's explained in my study material.... I have heard
people saying that they never understood subnetting properly from Microsoft,
until they studied CISCO... etc.
Many sources, for example, say: "Use the formula: 2 powered by the number of
borrowed bits ... blah, blah, blah" , but do not give details about it, etc.
I would explain the freaken formula starting with the possible combinations
of 0s and 1s and give examples as followes:

Example 1: Possible combinations with 4 bits

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

Total: 16 combinations or 2 to the power of 4

Example 2: Possible combinations with 3 bits

000
001
010
011
100
101
110
111

Total: 8 combinations or 2 to the power of 3

Example 3: Possible combinations with 2 bits

00
01
10
11

Total: 4 combinations or 2 to the power of 2

Example 4: Possible combinations with 1bit

0
1

Total: 2 combinations or 2 to the power of 1

Then, go ahead and explain why all 0s and all 1s are not used, and this way,
it would be no problem understanding "why the network number will be 0 if we
borrow just 1 bit".

Of course, nobody owes me any answer, but on the other hand, nobody has the
right to insult me and mock me for asking questions in newsgroups. Nobody
knows everything and more we learn, more we realize what ignorants we are.
Why am I always happy to help people for things that I know better than
them?

new guy

new guy, May 24, 2006
12. TwistyCreekGuest

new guy wrote:

<snip>

First of all, we're not here to do you homework for you no matter how

Second, your questions are off topic for ACS no matter how many times you
network admin stuff. There's dozens of forums specifically for that
material.

http://www.cisco.com/warp/public/701/3.html

Now. If you're still having trouble after thoroughly studying this Cisco
reference, GO BOTHER SOMEONE ELSE. This is a computer security group, not
alt.teach.annoying.little.kids.subnetting.

Got it?

Good.

TwistyCreek, May 24, 2006
13. Moe TrinGuest

On Wed, 24 May 2006, in the Usenet newsgroup alt.computer.security, in article
<8dQcg.184204\$P01.101713@pd7tw3no>, new guy wrote:

> "new guy" <new ymous> wrote

>> I am studying subnetting and I have a few question, if you do not mind.

1. What textbook are you using?
2. comp.protocols.tcp-ip might be a more appropriate newsgroup.

>> 1. why will the network number be 0 if we borrow just 1 bit?

That rather poorly framed question assumes a classful ('Class A', 'Class C,
etc. - superseded by CIDR in 1993) networking scheme. That may not be the
case. The 'network number' is that address where the bits in the 'host'
where the bits in the 'host' part of the address are all ones. The 'host'
part of the address is defined as that portion of the address where the
bits in the network mask are zero.

>> The ID of the first Subnetwork (0) is the same as the original network and
>> the broadcast ID of the second subnetwork (1) is the same as the broadcast
>> of the original network. However, I am missing something simple ( as it's
>> always the case and hoped somebody would give me at least a hint.

What is the question?

>Now, it's more obvious to me that such a simple question has nothing to do
>with "doing my homework" as some jerk called it; it was an oversight and it
>had to do with the way it's explained in my study material.... I have heard
>people saying that they never understood subnetting properly from Microsoft,
>until they studied CISCO... etc.

Microsoft was bludgeoned into using IP five years after they "invented" a
networking scheme that everyone else had rejected as unusable, and only 13
years after IP was developed. They still aren't comfortable with it. Cisco
has a bit more experience.

them, there is network, host, and broadcast, and nothing else matters. The
subnet is an administrative concept of how you divide a block of addresses
that may be assigned/allocated/available to you. If you want to divide a
network into 'sales' and 'engineering' (or any other criteria) the only
thing you have to know is that the resulting network mask has to be one of
32 possible values, and will _likely_ be one of a much smaller series -
perhaps /29 to /22 (255.255.255.248 to 255.255.252.0) for practical reasons.

>Many sources, for example, say: "Use the formula: 2 powered by the number of
>borrowed bits ... blah, blah, blah" , but do not give details about it, etc.

That sounds like a paraphrase off of RFC0950 which defined the Internet
Standard Subnetting Procedure in 1985. A major problem is that there are a
number of ways to define things like a network mask. /23, FFFFFE00,
255.255.254.0 and 11111111 11111111 11111110 00000000 all define the same
thing - which one are you comfortable with?

>I would explain the freaken formula starting with the possible combinations
>of 0s and 1s and give examples as followes:

[...]

>Then, go ahead and explain why all 0s and all 1s are not used, and this way,
>it would be no problem understanding "why the network number will be 0 if we
>borrow just 1 bit".

Except I still don't see what your question might be. My suggestion would be
to find a better text book. Perhaps if you looked at RFC1878 and saw the
examples, things might be more clear.

Old guy

Moe Trin, May 24, 2006
14. new guyGuest

"Moe Trin" <> wrote in message
news:...
> On Wed, 24 May 2006, in the Usenet newsgroup alt.computer.security, in
> article
> <8dQcg.184204\$P01.101713@pd7tw3no>, new guy wrote:
>
>> "new guy" <new ymous> wrote

>
>>> I am studying subnetting and I have a few question, if you do not mind.

>
> 1. What textbook are you using?
> 2. comp.protocols.tcp-ip might be a more appropriate newsgroup.

Thanks for the INFO.

>>> 1. why will the network number be 0 if we borrow just 1 bit?

>
> That rather poorly framed question assumes a classful ('Class A', 'Class
> C,
> etc. - superseded by CIDR in 1993) networking scheme. That may not be the
> case. The 'network number' is that address where the bits in the 'host'
> where the bits in the 'host' part of the address are all ones. The 'host'
> part of the address is defined as that portion of the address where the
> bits in the network mask are zero.

The question came out of the following statement, which was not related to
any specific scenario and it was not explained either: " If we borrow just 1
bit, the network number will be 0" .

> Microsoft was bludgeoned into using IP five years after they "invented" a
> networking scheme that everyone else had rejected as unusable, and only 13
> years after IP was developed. They still aren't comfortable with it. Cisco
> has a bit more experience.
>
> them, there is network, host, and broadcast, and nothing else matters. The
> subnet is an administrative concept of how you divide a block of addresses
> that may be assigned/allocated/available to you. If you want to divide a
> network into 'sales' and 'engineering' (or any other criteria) the only
> thing you have to know is that the resulting network mask has to be one of
> 32 possible values, and will _likely_ be one of a much smaller series -
> perhaps /29 to /22 (255.255.255.248 to 255.255.252.0) for practical
> reasons.

Thanks!

>
>>Many sources, for example, say: "Use the formula: 2 powered by the number
>>of
>>borrowed bits ... blah, blah, blah" , but do not give details about it,
>>etc.

>
> That sounds like a paraphrase off of RFC0950 which defined the Internet
> Standard Subnetting Procedure in 1985. A major problem is that there are a
> number of ways to define things like a network mask. /23, FFFFFE00,
> 255.255.254.0 and 11111111 11111111 11111110 00000000 all define the same
> thing - which one are you comfortable with?
>
>>I would explain the freaken formula starting with the possible
>>combinations
>>of 0s and 1s and give examples as followes:

>
> [...]
>
>>Then, go ahead and explain why all 0s and all 1s are not used, and this
>>way,
>>it would be no problem understanding "why the network number will be 0 if
>>we
>>borrow just 1 bit".

>
> Except I still don't see what your question might be. My suggestion would
> be
> to find a better text book. Perhaps if you looked at RFC1878 and saw the
> examples, things might be more clear.

Thanks again. I will do that!

new guy, May 30, 2006
15. raincoaterGuest

Hello, TwistyCreek !
You wrote:

> new guy wrote:
>
> <snip>
>
> First of all, we're not here to do you homework for you no

matter how
>
> Second, your questions are off topic for ACS no matter how many

times you

basic
> network admin stuff. There's dozens of forums specifically for

that
> material.
>
>
> http://www.cisco.com/warp/public/701/3.html
>
> Now. If you're still having trouble after thoroughly studying

this Cisco
> reference, GO BOTHER SOMEONE ELSE. This is a computer security

group, not
> alt.teach.annoying.little.kids.subnetting.
>
> Got it?
>
> Good.
>

Ouch!

raincoater, Jul 21, 2006