70-270 Difficulty...

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One thing I would say, is that ignore the TCP/IP section of 70-291, it asks you to memorize the table of Subnet Mask Notations.

There is a much simpler way to do it.

Code:

Example:

192.168.1.24 /28

This gives us a subnet mask of 255.255.255.240

So, of course in binary form this is:

11111111.11111111.11111111.11110000

So, the way I learned from Cisco how to find out what the subnet mask is with the /n notation is this:

The first digit in an octet represents 128, the second, 64.

Here is how it works..

1st > 128
2nd > 64
3rd > 32
4th > 16
5th > 8
6th > 4
7th > 2
8th > 1

So now we know what the values are for the ascending 1's in the octet.

Now we can use this instead of memorizing the Subnet Mask Notation table.

11111111 = 255
11111111 = 255
11111111 = 255
11110000 = 240

You get 240 because you're 'adding up' the 1's

128 + 64 + 32 + 16 = 240

You get 255 because:

128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255

That's how I do it, sorry if it's not explained clearly but this was done on the fly

 

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Very similar method to how I originally learnt...

I used to just write the numbers over the octet though. It's easier to view like this :-

E.G.







Qs

 

Yeah I use the same method as yourself Qs, as taught by the MS Course at QA, formally xpertise, in London.

 

Ah, sorry, I couldnt explain it much better, plus I wanted to give a bit of background instead of just diving in.

Apologies

 

Don't apologise Your explanation was good!

It's just easier to view if you write it down in a different format.

If it helps people, it's always good.

+rep for your original post.

Qs

 

Thanks Qs

Was just worried I had given a much more garbled answer than needed !

Dont wanna throw anyone off course !

Hope someone finds the above posts useful ^^

 

Don't worry! It's not hard! Trust yourself!

 

bin table starts at 1 I did think it started from 2.

256 128 64 32 16 8 4 2

I also learnt by bits borrowed.

128 |1
192 |2
224 |3
240 |4 - Qs
248 |5
252 |6
254 |7
255 |8

 

Best book for 70-270 is the XP Resource Kit, yes huge book but it contains the many best practices that the others do not have and which feature a lot on the exam. I failed 70-270 first time round and I used the traning kit and the Exam Cram 2 book. Second time around I made sure that I'd backed up my knowledge by looking up the areas covered by the exam in the Resource Kit...well I flew through the exam with a score of over 900 if I remember correctly. First attempt I got 675 (

 

Oops, didn't realise this was an old post lol!