CIDR

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Hi guys was wondering if you could clear somthing up for me

I'm not 100% sure I know how to work out a IP subnet mask using CIDR for example

192.168.22.55/22 subnet here would be 255.255.254.0 right ?

know by looking at the CIDR table you get 1,002 host but how ? you cant enter the /22 when you configure your IP address and I know the computer only sees bits of the 3rd octet so does that mean I can put any number in the 3rd octet and all the computers can still talk to each other ?

Any info you guys can give would be great I just can't seem to get my head around this atm.

 

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You might want to start with this:

http://compnetworking.about.com/od/workingwithipaddresses/l/aa021003a.htm

 

I'll probably get this wrong but WTF!!!

A /22 network gives you a mask of 255.255.252.0 this means that your network uses 22 bits of the 32 leaving 10 for the host portion. You therfore have 2 to the power 10 = 1024 possible host addresses (except that you need to subtract 2 from that total, one for the network and one for the broadcast address). So the actual range is as follows:
192.168.252.0 - Network address
192.168.252.1 - First usable address
192.168.255.254 - Last usable
192.168.255.255 - Broadcast

Er I think????

 

Giving it some more thought isn't 192.168.22.55/22 an invalid address????

 

dunno I just chose random numbers but you have given me it in a form I can understand. =)

Ok so here is another

213.113.188.99/15

255.127.0.0 - Network address
255.127.1.1 - First usable address
255.127.255.254 - Last usable
255.127.255.255 - Broadcast

So you only lose 2 host address and the amount of host avaible is 2 to the power of 17 ?

PS Tripwire that is a pukka site mate

 

Is that good?

 

As I predicted earlier, I got this wrong last night!!!

The address 192.168.22.55 wih a subnet mask of 255.255.252.0 is a valid address. Using this subnet would give you 61 subnets or segments each containing upto 1022 hosts, and the address you quoted would sit in the subnet
192.168.20.0 - Network address
192.168.20.1 - First usable
192.168.23.254 - Last usable
192.168.23.255 - Broadcast.

Now if you'll excuse me, I'm off for a lie down!!!!!

 

Yes Trip pukka is good, it is like "the dogs" (short for, the dogs bo!!ok$) or sweet, meaning good, or *wicked*, meaning good or down here *fair dinkums* meaning anything good or fair or sometimes used just to mean "oh really"

And I thought you knew English lol

Pete

 

Only in America.