ed network 15.1.1.1/24 tries to get to a web page on a server with the same IP network and mask, the rules of routing will indicate that they are on Chapter 36: IP Design the same network, SO the packet will never be forwarded to the default gateway. Some would argue that a firewall with NAT is the solution for poor IP design, but because the host will never forward the packets to the default gateway, they will never be NATed. Additionally, when companies form partnerships with other companies, they often link their networks together. A smart company will not link with a company that violates the IP rules, as it, too, will be affected, since it will inherit routes to the improperly used IP spaces. Remember, if there is a route in the routing table for a destination network, the default gateway is not involved. Should a valid public network be misused internally, your users will never be able to get to any services on that valid public network. Figure 36-1 shows an example of an improperly used public IP network. In this exam- ple, the world's most interesting web page has a legitimate IP address of 25.25.25.40 with a subnet mask of 255.255.255.0. Bob, in Company A, has an improperly used IP address of 25.0.0.15 with a subnet mask of 255.0.0.0. What is important to understand in this example is that even though the subnet masks are different, no one in either Company A or Company B can get to the world's most interesting web page. 25.25.25.40/24 25.25.25.0/24 Internet World's most interesting web page Company A Company B 25.0.0.0/8 192.168.1.0/24 25.0.0.15/8 192.168.1.18/24 Sally Figure 36-1. Invalid use of a public IP network Bob cannot get to the world's most interesting web page because, as far as the routers are concerned, he is on the same IP network as the destination. The IP stack on his machine will assume that because the destination is on the same network, it does not need to forward the packets to the default gateway. In this case, Bob's computer will either send the packets to a local device (should on