If you installed OpenBSD over the Internet, at least one Ethernet card should be configured and working. But if you installed from CD, you didn’t need to configure the network to install OpenBSD. If you installed OpenBSD on one network and want to move the machine to another network, you’ll need to reconfigure the network on your system.
I cover network principles in Chapter 11 and configuration in Chapter 12, but this brief entry will attach valid network addresses to your system, install a default route, and get DNS resolution working. If you’re not sure what to do here, don’t do anything until you read the later chapters.
To make network changes take effect, you can either reboot or run the network startup script /etc/netstart