A network administrator is connecting hosts A and B directly through their Ethernet interfaces, as shown in the illustration. Ping attempts between the hosts are unsuccessful. What can be done to provide connectivity between the hosts?
A crossover cable should be used in place of the straight-through cable. The subnet masks should be set to 255.255.255.0. First, if you have two hosts directly connected, as shown in the graphic, then you need a crossover cable. A straight-through cable won't work. Second, the hosts have different masks, which puts them in different subnets. The easy solution is just to set both masks to 255.255.255.0 (/24). This problem is due to the misconfiguration of subnet mask as well as the fact that a straight-through…show more content… Also, the message transfer unit (the maximum size of Ethernet frames the kernel will generate for this interface) has been set to the maximum value of 1500 bytes. All these values can be overridden with special options that will be described later.
Quite similar to the loopback case, you now have to install a routing entry that informs the kernel about the network that can be reached through eth0. For the Virtual Brewery, you would invoke route as
# route add -net 191.72.1.0
At first, this looks a little like magic, because it's not really clear how route detects which interface to route through. However, the trick is rather simple: the kernel checks all interfaces that have been configured so far and compares the destination address (191.72.1.0 in this case) to the network part of the interface address (that is, the bitwise and of the interface address and the netmask). The only interface that matches is
