I am running RVM on Linux Mint 17 and am hitting a recurring, random, temporary error when I
Gem::RemoteFetcher::UnknownHostError: no such name (https://rubygems.org/gems/some_gem)
Probably you should update your rubygems, if you are not using last version https://github.com/rubygems/rubygems/issues/762
It also can be an issue with your DNS setup, check
If it fails - it can be problem with DNS server that you are using.