After updating serverB's network configurations, anadministrator notices that serverA, which resides in a different subnet, is unable to communicate with serverB via ssh or telnet. As ping's to the server fail, the administrator logs onto serverB via a console and finds an available interface en0 in the 'up' state. From the console connection, en0 can communicate with other servers in the same subnet. What is the most likely cause of the problem?（）

• A、en0 has no associated ip address.
• B、serverB is missing its default route.
• C、serverB and serverA cannot connect due to a firewall.
• D、en0 has been set up to block traffic from servers that are in different subnets.