[KLUG Members] some network questions

[Chris Hansen]

Bert Bbbink wrote:

>The network/host part is set by the netmask, what basically means that the
>last bit set (from left to right) marks the end of the network part. What
>if I set my netmask like 255.254.255.0 ? A easily made typing error.
>If again the last bit set from left to right marks the end of the network
>part my network ends at the 15th bit.
>
Chris Hansen writes:

Well, I think you mean the 16th bit (if it's the difference between 254 
and 255 in the 2nd octet that is).  All the positions of the netmask are 
useful and used by any OS with a full functional tcp/ip stack.  You 
usually only use the 4th octet on most networks because you're generally 
dealing with less than 254 usable IPs on your network.  What you want to 
look into Bert is "subnetting" to get a better understanding of the 
usefulness of the netmask.

http://en.wikipedia.org/wiki/Ipv4_subnetting_reference

As far as your compression question, I'm not real clear, but the RARP 
comment makes me think your running into subnet/routing probs.  Say you 
have a 192.168.1.0 network and a 192.168.2.0 network.. if you give a 
machine on the 192.168.1.0 network a 255.255.0.0 subnet mask it's not 
going to ask it's default gateway to help it get to 192.168.2.0's network.