a basic subnetting question

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thankyou i think im gonna quit while im ahead. and go back and do some revision. :P

is the basis of my first post on the right lines or an i just being really thick. if its any excuse im tired.

 

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Yes - you were, in effect, pointing out that in some circumstances it isn't just the last octet that defines the host.

Harry.

 

Another thing i got wrong was the ANDing of the IPaddresses.

i got it backwards. as 1 AND 1 = 1 where as 1 AND 0 =0

so
11000000.10101000.00000001.00000001
AND
11111111.11111111.11111111.00000000
Equals
11000000.10101000.00000001.00000000

mabe i should go back and re write that post so its all right.

 

Man, I never thought this thread would go the distance. Keep going, gang.

 

Just connect all machines to an ADSL connection, subnet the mac address with an DHCP binary digit of 4, apply the 192.168.252.1 to the first host on the network DNS virtual server. And bobs your uncle.

P.s make sure MS-DOS is installed on all routers, or you may get some problems.

Had the same problem myself done this and it worked.

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The guy that made this thread is having a laugh, cant be done, given the fact you have one network address and three networks. And you cant subnet.

 

I am not sure if this has been mentioned in a different thread but you can use this site to help with practising subnetting. I used it as part of my preparations to obtaining the CCNA - with enough time you can do subnetting in your head !

 

there was a way my tutor showed me how to do it, but when written down it doesnt really make much sence.

i will try and explain the table as best i can

Code:

128      64       32     16     8    4     2        1
0         0        0       0        0   0     0        0


so if the first bit is on you have split into 2 networks

0-127 and 128-254
if the seccond bit is on you split into 3 networks
0-64  65-128- 129-192  193-254
and this carys on. 

now if its for the 4th octet you can use the first and last address as there broadcast and netID so the table goes like this

first bit on 
1-127  129-254
seccond bit
1-63 66-127  129-191 194-254

it works on paper but its hard to explain.

 

Subnetting is not that hard when you get your head round it.

Simple way to think of it is this.

If i borrow 1 bit i get 2 networks
2 bits | 4 networks
3 bits | 8 networks
4 bits | 16 networks
5 bits | 32 networks
6 bits | 64 networks
7 bits | 128 networks
8 bits | 256 networks

see the trend?

All thats left to do is take away 2 networks to compensate for the network and broadcast address.

The same can be done for host, but dont count the number of bits borrowed but the number of bits that have not been borrowed

i.e

a /27 bit mask

255.255.255.1110 0000

3 bits borrowed, 5 not borrowed, use the the chart 5 = 32 hosts - 2 for net and broadcast= 30 hosts

Hope that makes sense.

 

it makes more sence written that way. i just need alot more practice at it before i go in for my 70-291 exam.