It is very possible to connect through the command line only. We need to know a few things first though, like say what it is that you are running. If it is debian, or one of its children, the config files are in /etc/network/interfaces. I like to use vim, so as root I make sure the file is set to receive a dhcp address from the network. If you're in red hat, the path to your files is /etc/sysconfig/network-scripts/ifcfg-eth0. The file should read like this to accept a dhcp address:
A dynamic address is one that can change. Static is just that, it never changes. There is no difference in connection quality, just a question of how easy it is for people to reach your machine. With static you can run mail, dns, whatever because you have ficed addresses. You can run those apps with a no-ip solution, but you don't need 3rd party scripts to get a website or anything else up with static.