e exist with the same IP address as the world's most interesting web page), or fail to resolve the IP address to a local MAC address. Either way, Bob will never be able to see the world's most interesting web page. Public Versus Private IP Space Assuming Company B would like its employees or servers to be able to get to Company A's devices (why else would there be a link?), the router connecting Company B to Internet must have a route to Company A's network-in this case, 25.0.0.0255.0.0.0. Because the default route will only be used if there are no matching routes in the routing table and because, in this case, there is a matching route in the routing table, the packets destined for the world's most interesting web page will be forwarded to Company A. Therefore, Sally will not be able to access the world's most interesting web page either. Variable Length Subnet Masking (VLSM) is the best thing to happen to IP networking since subnet masks. In a nutshell, according to what we'll call classful subnetting rules, if a network is divided into subnets, each subnet within the classful network must be the same size. Figure 36-2 shows the ways in which a Class C network can be divided. Under the traditional classful rules, these are the only divisions possible. The reason for this is the binary nature of the subnet mask. When IP was developed, there were more IP addresses available than anyone could have possibly wanted-or SO we all thought! But as the world progressed, we quickly discovered that we were running out of IP address space at an alarming rate. Some bright minds determined that if the rules of subnetting could be altered a bit, we could give ourselves some breathing room. The result was VLSM. VLSM states that when a network is subnetted, the individual subnets do not need be of equal size. The caveat is that the subnets must still follow the rules of binary; that is, they must exist where they would normally fall when you're subnetting using the traditional rules. Figure 36-3 shows examples of a normally subn