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CCNA math question
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| ok first off, in my defence let me say I have an economics degree so im
not as stupid as I may seem, however...
im hopeless at mental arithmetic and whilst im finding the academy
program pretty easy so far (I find subnetting easy for example) I simply
cannot convert from decimal to binary (and vica versa) in my head. I
have to do it on paper (takes about 20 seconds). that being the case, do
I honestly have any chance of making it through?
| |
| BlueFire 2004-02-17, 3:25 am |
| Yep cause they give u paper to work out the questions or they did when i did
it
now i think they give like a mini white board
"kad" <kad_aus@S-P-AMziplip.com> wrote in message
news:3510e2d63c76ca604a23f2c25
192c4e7@news.teranews.com...
> ok first off, in my defence let me say I have an economics degree so im
> not as stupid as I may seem, however...
> im hopeless at mental arithmetic and whilst im finding the academy
> program pretty easy so far (I find subnetting easy for example) I simply
> cannot convert from decimal to binary (and vica versa) in my head. I
> have to do it on paper (takes about 20 seconds). that being the case, do
> I honestly have any chance of making it through?
| |
| Flixis 2004-02-17, 3:25 am |
| kad <kad_aus@S-P-AMziplip.com> wrote in
news:3510e2d63c76ca604a23f2c25
192c4e7@news.teranews.com:
> ok first off, in my defence let me say I have an economics degree so
> im not as stupid as I may seem, however...
> im hopeless at mental arithmetic and whilst im finding the academy
> program pretty easy so far (I find subnetting easy for example) I
> simply cannot convert from decimal to binary (and vica versa) in my
> head. I have to do it on paper (takes about 20 seconds). that being
> the case, do I honestly have any chance of making it through?
Sure, as long as you can do it..there is enough time and the place I
went to gave me plenty of scratch paper. Your biggest problem might be
converting from HEX to decimal, or HEX to binary. I bring it up for a
reason :-) You might want to find a mental short cut to find your way.
I find (decimal to binary) it easier to think higher to lower on the
binary chart. For example: 157 Which is of course greater than 128, 128
minus 157 is 29. 29 is less than 64, and 32, but not 16.
So far I have 128 + 16 = 144, which leaves us with 13 left, which I can
now do in my head (8 + 4 + 1).
10011101
In summary, you will need know subnetting and dec/bin/hex conversion
very well. When I say you'll need to know subnetting.....
What is the network address of 192.168.1.138/29 ?
Her are a couple tools I find usefull, you probably won't need the
subnet section 
==============================
==============================
============
I have two charts that help me. The first chart deals with subnet
masks, CIDR notation, number of IP's, number of subnets in a class C,
and class ranges (first octet rule)
First chart: You'll need eight columns, and four rows:
CIDR /24 /25 /26 /27 /28 /29 /30 /31 /32
IP's 256 128 64 32 16 8 4 2 1
Mask 0 128 192 224 240 248 252 254 255
Subnets 1 2 4 8 16 32 64 128 256
First Row is the CIDR Notation. As you can see you just start from the
right and count down from 32.
Second row is the amount of IP's in a subnet. If we are talking about
"valid IP's" or hosts, you would subtract two (can't use the first, or
the last). With this row you start at the right again and keep doubling
starting from 1, 1x2=2, 2x2=4, 2x4=8 etc)
Third row is the subnet mask: ie 255.255.255.192
Again start at the right and subtract the number above it: 255-1=254,
254-2=252, 252-4=248 etc)
Fourth row: how many subnets each mask will create in a class C
(255.255.255.0) Start at the left this time, start with 1 and double.
As far as network and broadcast, I find it helpful to think of radio
broadcasts in the sky. Network on the ground (bottom or lower address)
and broadcast in the air (top or higher address)
If you look at the "Mask" row, you can kinda see the classes (first
octet rule) Starting from the left:
class A Class B Class C Class D Class E
0 - 126 128-191 192-223 224-239 240-247
127 is the loopback and not usable as a host.
Second chart
OSI Encapsulation
Application --- Data
Presentation
Session
Transport ----- Segments
Network ------- Packets
Data Link ----- Frames
Physical ------ Bits
I tried to create a pneumonic for the data encapsulation flow and all I
came up with is "don't suck penis for bucks" If someone has a better
one, please let me know :-)
I assume everyone knows one for the OSI model:
Please Do Not Throw Sausage Pizza Away
or
All People Seem To Need Data Processing
Remember that the User information is is converted to Data at the
Application layer, and everything else falls into place at the bottom.
Good Luck!
| |
|
| <snip>
| Second chart
| OSI Encapsulation
|
| Application --- Data
| Presentation
| Session
| Transport ----- Segments
| Network ------- Packets
| Data Link ----- Frames
| Physical ------ Bits
|
| I tried to create a pneumonic for the data encapsulation flow and all I
| came up with is "don't suck penis for bucks" If someone has a better
| one, please let me know :-)
|
| I assume everyone knows one for the OSI model:
| Please Do Not Throw Sausage Pizza Away
| or
| All People Seem To Need Data Processing
Always used "Dave had Six Pints For Breakfast" and "A Pink Sausage Takes No
Damned Prisoners" myself :-)
Guess it doesn't matter as long as it sticks in your memory and you can
remember what the real words are.
| |
|
|
Yes.... Take the time to subnet... You've got plenty of
time.
"kad" <kad_aus@S-P-AMziplip.com> wrote in message
news:3510e2d63c76ca604a23f2c25
192c4e7@news.teranews.com...
> ok first off, in my defence let me say I have an economics degree so im
> not as stupid as I may seem, however...
> im hopeless at mental arithmetic and whilst im finding the academy
> program pretty easy so far (I find subnetting easy for example) I simply
> cannot convert from decimal to binary (and vica versa) in my head. I
> have to do it on paper (takes about 20 seconds). that being the case, do
> I honestly have any chance of making it through?
| |
| Cyberus 2004-02-17, 10:25 am |
| Excellent stuff there Flixis, thanks alot, subnetting was starting to worry
me ...cheers!!!
"Flixis" <certcisco@nospamFlixis.nospamcom> wrote in message
news:Xns949217A1392A8nospamcer
tciscoatFli@68.1.17.6...
> kad <kad_aus@S-P-AMziplip.com> wrote in
> news:3510e2d63c76ca604a23f2c25
192c4e7@news.teranews.com:
>
>
> Sure, as long as you can do it..there is enough time and the place I
> went to gave me plenty of scratch paper. Your biggest problem might be
> converting from HEX to decimal, or HEX to binary. I bring it up for a
> reason :-) You might want to find a mental short cut to find your way.
>
> I find (decimal to binary) it easier to think higher to lower on the
> binary chart. For example: 157 Which is of course greater than 128, 128
> minus 157 is 29. 29 is less than 64, and 32, but not 16.
> So far I have 128 + 16 = 144, which leaves us with 13 left, which I can
> now do in my head (8 + 4 + 1).
>
> 10011101
>
> In summary, you will need know subnetting and dec/bin/hex conversion
> very well. When I say you'll need to know subnetting.....
>
> What is the network address of 192.168.1.138/29 ?
>
> Her are a couple tools I find usefull, you probably won't need the
> subnet section
>
> ==============================
==============================
============
>
> I have two charts that help me. The first chart deals with subnet
> masks, CIDR notation, number of IP's, number of subnets in a class C,
> and class ranges (first octet rule)
>
> First chart: You'll need eight columns, and four rows:
>
> CIDR /24 /25 /26 /27 /28 /29 /30 /31 /32
> IP's 256 128 64 32 16 8 4 2 1
> Mask 0 128 192 224 240 248 252 254 255
> Subnets 1 2 4 8 16 32 64 128 256
>
> First Row is the CIDR Notation. As you can see you just start from the
> right and count down from 32.
>
> Second row is the amount of IP's in a subnet. If we are talking about
> "valid IP's" or hosts, you would subtract two (can't use the first, or
> the last). With this row you start at the right again and keep doubling
> starting from 1, 1x2=2, 2x2=4, 2x4=8 etc)
>
> Third row is the subnet mask: ie 255.255.255.192
> Again start at the right and subtract the number above it: 255-1=254,
> 254-2=252, 252-4=248 etc)
>
> Fourth row: how many subnets each mask will create in a class C
> (255.255.255.0) Start at the left this time, start with 1 and double.
>
> As far as network and broadcast, I find it helpful to think of radio
> broadcasts in the sky. Network on the ground (bottom or lower address)
> and broadcast in the air (top or higher address)
>
> If you look at the "Mask" row, you can kinda see the classes (first
> octet rule) Starting from the left:
> class A Class B Class C Class D Class E
> 0 - 126 128-191 192-223 224-239 240-247
> 127 is the loopback and not usable as a host.
>
>
> Second chart
> OSI Encapsulation
>
> Application --- Data
> Presentation
> Session
> Transport ----- Segments
> Network ------- Packets
> Data Link ----- Frames
> Physical ------ Bits
>
> I tried to create a pneumonic for the data encapsulation flow and all I
> came up with is "don't suck penis for bucks" If someone has a better
> one, please let me know :-)
>
> I assume everyone knows one for the OSI model:
> Please Do Not Throw Sausage Pizza Away
> or
> All People Seem To Need Data Processing
>
> Remember that the User information is is converted to Data at the
> Application layer, and everything else falls into place at the bottom.
>
>
> Good Luck!
| |
| forbesl 2004-02-17, 2:00 pm |
| kad,
Don't worry about not being able to do it in your head. You will be able to use a sheet to do it with. If you're not use to constantly working with subnetting, it takes a while for you to do it in your head. | |
| Netwerkz 2004-02-17, 10:24 pm |
|
"kad" <kad_aus@S-P-AMziplip.com> wrote in message
news:3510e2d63c76ca604a23f2c25
192c4e7@news.teranews.com...
> ok first off, in my defence let me say I have an economics degree so im
> not as stupid as I may seem, however...
> im hopeless at mental arithmetic and whilst im finding the academy
> program pretty easy so far (I find subnetting easy for example) I simply
> cannot convert from decimal to binary (and vica versa) in my head. I
> have to do it on paper (takes about 20 seconds). that being the case, do
> I honestly have any chance of making it through?
You will be fine.
Before you start your test, use your scratcfh paper
to write down tables of info:
Tables of 2's: 2^1 thru 2^16
Tables of multiples: 8's, 16's and 32's
Table of "standard" subnet masks (128,192,224,240,248,252, 254) and
their matching bit locations
(from left to right bit position 1=128,2=192,3=224, etc)
The real time-saver for me was using the multiple of 8, 16, and 32 tables.
It made it really easy for figure out what subnet a host was on.
Good luck..
| |
|
| >In summary, you will need know subnetting and dec/bin/hex conversion
>very well. When I say you'll need to know subnetting.....
>
>What is the network address of 192.168.1.138/29 ?
if thats typical of the questions i will be facing, then im pretty
confident. im just stressing out about time. how much time for instance
could you reasonably devote to that question? anyone?
>Second chart
>OSI Encapsulation
>
>Application --- Data
>Presentation
>Session
>Transport ----- Segments
>Network ------- Packets
>Data Link ----- Frames
>Physical ------ Bits
>
>I tried to create a pneumonic for the data encapsulation flow and all I
>came up with is "don't suck penis for bucks" If someone has a better
>one, please let me know :-)
lol, thats actually pretty good, ill use it  very useful post, thanks.
| |
|
| In article <CjAYb.335689$I06.3491671@attbi_s01>, Netwerkz101@comcast.net
says...
> Tables of 2's: 2^1 thru 2^16
> Tables of multiples: 8's, 16's and 32's
> Table of "standard" subnet masks (128,192,224,240,248,252, 254) and
> their matching bit locations
> (from left to right bit position 1=128,2=192,3=224, etc)
>
> The real time-saver for me was using the multiple of 8, 16, and 32 tables.
> It made it really easy for figure out what subnet a host was on.
>
> Good luck..
thanks for suggesting that, will definately help speed things up for me
overall
| |
| Steve 2004-02-18, 12:25 pm |
| On Tue, 17 Feb 2004 07:19:23 GMT, Flixis
<certcisco@nospamFlixis.nospamcom> wrote:
>kad <kad_aus@S-P-AMziplip.com> wrote in
> news:3510e2d63c76ca604a23f2c25
192c4e7@news.teranews.com:
>
<SNIP>
>Sure, as long as you can do it..there is enough time and the place I
>went to gave me plenty of scratch paper. Your biggest problem might be
>converting from HEX to decimal, or HEX to binary. I bring it up for a
>reason :-) You might want to find a mental short cut to find your way.
>
Hex to Binary and vice versa are pretty easy - 1 hex digit corresponds
to 4 bits.
So, 0xF == 1111, hence 0xFF == 1111 1111
<SNIP>
Steve
| |
| Fred Atkinson 2004-02-18, 5:25 pm |
| On Tue, 17 Feb 2004 05:13:45 GMT, kad <kad_aus@S-P-AMziplip.com>
wrote:
>ok first off, in my defence let me say I have an economics degree so im
>not as stupid as I may seem, however...
>im hopeless at mental arithmetic and whilst im finding the academy
>program pretty easy so far (I find subnetting easy for example) I simply
>cannot convert from decimal to binary (and vica versa) in my head. I
>have to do it on paper (takes about 20 seconds). that being the case, do
>I honestly have any chance of making it through?
No one is expected to be able to convert from decimal to binary
and back in their head. Don't lose any sleep over that.
I don't know how complex the problem you are describing was, but
twenty seconds seems awfully fast for most of them.
Fred
| |
| Andrew 2004-02-29, 10:25 pm |
| I had difficulty understanding subnetting until I read Todd Lammle's CCNA
Study Guide for the 640-607.
http://www.sybex.com/sybexbooks.nsf...r />
50/69c31b8
9d87fe50a88256bca006f1de1!Open
Document
ISBN: 0-7821-4167-6
After reading through his explanations and doing the exercises in the book,
I now can actually subnet in my head. It definately takes practice and
knowing powers of two very well. I don't know what materials are best for
preparing for the current CCNA exam, but I would not hesitate to recommend
this book just for its explanation of subnetting.
Andrew
"Fred Atkinson" <fatkinson@mishmash.com> wrote in message
news:6jl730td5d40dv3g8768ibemt
dsjbt0512@4ax.com...
> On Tue, 17 Feb 2004 05:13:45 GMT, kad <kad_aus@S-P-AMziplip.com>
> wrote:
>
>
> No one is expected to be able to convert from decimal to binary
> and back in their head. Don't lose any sleep over that.
>
> I don't know how complex the problem you are describing was, but
> twenty seconds seems awfully fast for most of them.
>
>
>
> Fred
>
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