New School. New subnets that just dont make sence to me.

[sreiach]

I've just started in a new 'laptop' school. Right now every laptop has a fixed IP. (ugh). I was looking into switching to DHCP when I found the following.

 

My IP is 192.168.1.33 with the subnet of 255.255.224.0. (Not even in the right class). Anyway, the current tech is issuing out IP's past 192.168.19.x which if im using my subnet calculator correctly it is going into ip range that 'in theory' don't exist for one subnet..

 

It should go from from 192.168.0.1 to 192.168.15.254 for the first one. The second one is from 192.168.16.1 to 192.168.31.254 but considering we have no routers thats not going to fly.

 

So how is it that these computers in 192.168.19.x work? What am I missing?

[GrumbleDook]

No router at all? Not even a Layer 3 switch that is doing some of it? Is you gateway doing some of the routing?

[Joedetic]

The way I understand it a subnet mask of 255.255.224.0 will allow you to have from 192.168.0.1 up to 192.168.31.254 without requiring routers. There are 5 bits being borrowed from the third octet to add to the number of hosts.

 

So if you borrow 5 bits that's 0-31 (if you add the 1,2,4,8 and 16 that you're borrowing).

 

That is the way we did it on CCNA 1 so that machines with a differing third octet in their ip addresses could communicate without using routers.

 

Please note that i could be quite wrong seeing as i'm out of practice.