Could not resolve host (nil); Unknown error

Question

Trying to install arch linux into virtualbox...
I got it to boot and everything, got my internet set up (I think), installed virtualbox guest stuff, and then had to reboot.
I try to do sudo pacman -S xorg-twm xorg-xclock xterm so that I can test X before installing a desktop enveiroment..
It then asks me for my password, the Y/N thing, etc.
And then I get a whole bunch of lines saying "error: failed retrieving file [filename] from [somewhere] : could not resolve host (nil); Unknown error"
And after that it says error: failed to commit transactions (download library error)
I follow this guide (http://wideaperture.net/blog/?p=3851), I am currently right above step 17.
Anyone knows what to do? I'm installing Arch Linux for the first time so I'm a total newbie.

Answer 1

Type journalctl with sudo, then push the end key to go at the last messages.
The guide you followed said :
sudo systemctl enable [email protected]
But with rescent archlinux changes, as you said with the result of 'ip addr', the base name of ethernet device has changed to enp0s3, maybe that's why you don't have the network. First disable the previous command :
sudo systemctl disable [email protected]
Then enable with the right name
sudo systemctl enable [email protected]
Either way, paste here the logs of journalctl (just type if you see some errors) after doing a
sudo systemctl restart dhcpcd
We never know, but have you checked your ethernet cable is plugged in?
For the screenshots, when I'm in virtualbox and do left ctrl+e, a window pop up to save the .png...