Network Connectivity in Ubuntu
Ubuntu, by default, is configured for DHCP. You can verify this by examining some configuration files related to networking:
less /etc/dhcp3/dhclient.conf less /etc/network/interfaces
In the default interfaces file, edit the last lines thusly:# The primary network interface
auto eth0
iface eth0 inet dhcp
where auto eth0 is the recommended change. Refresh the DHCP relationship by running sudo ifdown eth0; sudo ifup eth0. In the Microsoft Windows world, this is equivalent to ipconfig /release; ipconfig /renew. What also may be handy is to restart the network: /etc/init.d/networking restart. This sort of weirdness may be going on with an Ubuntu server installation because a server is supposed to have a static IP address. A step-by-step Ubuntu server set up is at howtoforge.com, “ISP Server Setup—Ubuntu 5.10 ‘Breezy Badger.’”