subnetting ccna help

~Stevief~

~Stevief~

~Stevief~

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Joined
23 Oct 2004
Posts
123
Location
Scotland
I've got my semester 1 exam coming up after christmas, any ccna people help this sink in as my brain is turning to mush :confused:

132 64 32 16 8 4 2 1

working from the left side is subnets,right side hosts i think

so if i needed a network of 25 users i would count from right side 2/4/8/16/32, so my address table will go up in 32's

ie 0 (in here would be usable addresses) 31
32 63
64 127
128 255
256

am i on the right track as i'm not sure thats right :confused:

Also what does the /26 mean??
 
hail hail said:
I've got my semester 1 exam coming up after christmas, any ccna people help this sink in as my brain is turning to mush :confused:

132 64 32 16 8 4 2 1

working from the left side is subnets,right side hosts i think

so if i needed a network of 25 users i would count from right side 2/4/8/16/32, so my address table will go up in 32's

ie 0 (in here would be usable addresses) 31
32 63
64 127
128 255
256

am i on the right track as i'm not sure thats right :confused:

Also what does the /26 mean??
Click to expand...
Sounds like you need to go over your coursework again matey ;)
The /26 is how many 1s you have in the binary octets signifying the subnet
so for example /24 is
255.255.255.0
which means you have 24 1s
The subnet address translates from decimal to binary as
11111111.11111111.1111111.00000000

With calculating what hosts are usable you examine the octet after the last 255 octet. so for example /26
255.255.255.192
which is in binary
11111111.11111111.11111111.11000000
You take the 192, and subtract that from 256, this leaves you with 64, which means your subnet goes up in groups of 64.
Now, in the group of 64, the first number of each group (0,64,128,192) is the network address (and therefore not a valid IP address), and the LAST IP address in the range (63,127,191) is the broadcast address and also not a valid choice for an IP address.

So in this example you would have 4 subnets
1)
Subnet Address: x.x.x.0
Broadcast Address: x.x.x.63
Valid IPs: x.x.x.1 - x.x.x.62
2)
Subnet Address: x.x.x.64
Broadcast Address: x.x.x.127
Valid IPs: x.x.x.65 - x.x.x.126
3)
Subnet Address: x.x.x.128
Broadcast Address: x.x.x.191
Valid IPs: x.x.x.129 - x.x.x.190
4)
Subnet Address: x.x.x.192
Broadcast Address: x.x.x.255
Valid IPs: x.x.x.193 - x.x.x.254

I'm 99% sure all these numbers are right, but there are a lot of them, so I apologise if I got anything wrong :)
 
Oh don't worry about coming back into the thread and saying thanks or that there's something you didn't understand by the way, I spend five minutes of my half hour lunch typing up explanations of networking concepts to people who don't read their coursework properly just for the thrill of hitting keys on my keyboard.
 
JollyGreen said:
Oh don't worry about coming back into the thread and saying thanks or that there's something you didn't understand by the way, I spend five minutes of my half hour lunch typing up explanations of networking concepts to people who don't read their coursework properly just for the thrill of hitting keys on my keyboard.
Click to expand...

:D
 
LOL, Thanks for the reply, it made a lot of sense. Serves me right for cheating and using subnet calcs while practicing :o

ps, I've been working up north and had no time to reply...sorry but very grateful for the reply :D
 
hail hail said:
LOL, Thanks for the reply, it made a lot of sense. Serves me right for cheating and using subnet calcs while practicing :o

ps, I've been working up north and had no time to reply...sorry but very grateful for the reply :D
Click to expand...

btw
sigs bad. no gifs dude

/edit
pwned from orbit
 
Last edited:
lol
you learn all these things but with it becomming more complex for us to deal with (being base 10 beings by and large) when will you actualy have to work it out for yourself without using a subnet calc etc to check?
back at college we had to be able to do basic maths in binery octal and hex.
A1
D3+
=
174 (372 dec)

etc

but why? when am I ever going to have to do that?


also, op, imo you should be left to swing, you went on the course and should have paid attention rather than cheating.
 
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