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## Network Diagram question

This might not be relevant to this forum but since this is the technical forum, I'll just give it a shot.

In a network diagram what does it mean with 192.168.0.1\24
or \34 ... what if two different ip series have the same \xx ending?

Does this got with the netmask to do?
Last edited by d_l0rd; 05-26-2004 at 08:53 AM.

2. Junior Guru Wannabe
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That \xx is how many bits are the network address. Each octet is one byte... or 8 bits. That \24 means the first 24 bits are the network address... so 192.168.0 is the network and .1 is the address specific to the host, which uses the last 8 bits.

\24 is the same as a netmask of 255.255.255.0 - a standard class C network.
\16 would be 255.255.0.0 - a class B network
\8 is 255.0.0.0 - a class A network

I'm assuming \34 was a typo... If you've got machines with a \34 on the network there's some serious issues since the max is \32

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thanks!

yeah 34 was wrong it was 30 and 32.

What does this mean in the real world? If I have more than 24 that would limit my serie of IP's right?

So if I have 32 I can only have one? or?

I have seen 30 and 32 alot on equipment like routers etc. connected to the internet.

4. Junior Guru Wannabe
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Ok, the netmask at the end defines how many IP addresses are in the subnet.

Do you like maths? I like maths... here we go...

The number of IP addresses in a subnet can be calculated like this:

so thats 2, raised to the power of 32 (the total number of bits in an IP address) minus the netmask (the number of bits that remain static in that IP address)

Lets try it out, (I know you want to)... lets take your netmask of /32

that gives us 2^(32-32) ... 2^0 = 1 ... so you only get 1 IP address

the /30 ... 2^2 ... gives us 4 IP addresses.

so using this same method you can see that /24 would give 256 addresses, etc. etc. etc.

Now we get onto usable IP addresses, yup, some IP addresses are not usable. The general rule is, take the total number of IP addresses, and subtract 3, this is because the router generally requires an all-zero broadcast address, an all-one broadcast address, and of course an address on the router itself.

Probably loads missing from that, if you need more details, shout.

5. Junior Guru Wannabe
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Originally posted by d_l0rd
thanks!

yeah 34 was wrong it was 30 and 32.

What does this mean in the real world? If I have more than 24 that would limit my serie of IP's right?

So if I have 32 I can only have one? or?

I have seen 30 and 32 alot on equipment like routers etc. connected to the internet.
Yes, using numbers other than 8, 16, and 24 gets more complex, but it does limit the amount of IPs you can have to a number lower than what is standard for whatever class of network you are working with.

32 would mean that IP address alone, then entire thing, equivalent to a netmask of 255.255.255.255.

30 would be a case of more advanced subnetting, which it's been awhile since I've had to mess with it, so need to read up myself before I can explain it in terms that someone who is relatively new to the concept could understand easily (don't take any offense to that, it's difficult to understand at first, took me quite awhile to grasp it).

6. Web Hosting Master
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This IP calculator might be of interest -
http://www.pkostov.de/ipcalc.html

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Thanks alot folks!

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