Ubuntu's New DNS: Unknown Host
If you're the type of person who installs Ubuntu's server edition, you're also likely the sort of person who knows how to configure network settings. For most distributions, especially those based on Debian, the process is a bit strange, but familiar.
To configure the various interfaces, you edit /etc/network/interfaces and add the appropriate IP information, along with the gateway address. That doesn't complete the process, however, because if you manually configure the network interfaces, you need to add the DNS servers manually to the /etc/resolv.conf file. That's the way it's always been, and I never put much thought into it—until Canonical changed the way the resolv.conf file works.
I'll admit, my initial reaction was one of frustration, but once I got over myself, I have to say it makes much more sense to add the DNS configuration right into the /etc/network/interfaces file as well. My only complaint is that there aren't comments in either the /etc/resolv.conf file or the /etc/network/interfaces file on actually how to do it! (Thankfully, there is a note in /etc/resolv.conf warning that any changes will be overwritten, but no hints on how to make changes properly.)
The process, as it turns out, is rather simple. In /etc/network/interfaces, simply add a couple lines to the end of the stanza for a particular interface—for example:
# The primary network interface
iface eth0 inet static
You'll notice the last three lines contain a few unfamiliar directives. They are fairly self-explanatory, but important to know. Once added to the /etc/network/interfaces file like above, the /etc/resolv.conf file is populated with the proper information when the network is activated. It's fairly simple, and it makes sense to have all the settings in one spot—but frustrating if you don't know about the changes!