instruction: Create a Dockerfile for fundamentals
output: ```dockerfile
  From a network architecture point of view, all
  containers on a given Docker host are sitting on bridge interfaces. This
  means that they are just like physical machines connected through a
  common Ethernet switch; no more, no less.How mature is the code providing kernel namespaces and private
  networking? Kernel namespaces were introduced between kernel version
  2.6.15 and
  2.6.26.
  This means that since July 2008 (date of the 2.6.26 release
  ), namespace code has been exercised and scrutinized on a large
  number of production systems. And there is more: the design and
  inspiration for the namespaces code are even older. Namespaces are
  actually an effort to reimplement the features of OpenVZ in such a way that they could be
  merged within the mainstream kernel. And OpenVZ was initially released
  in 2005, so both the design and the implementation are pretty mature.Control groupsControl Groups are another key component of Linux containers. They
  implement resource accounting and limiting. They provide many
  useful metrics, but they also help ensure that each container gets
  its fair share of memory, CPU, disk I/O; and, more importantly, that a
  single container cannot bring the system down by exhausting one of those
  resources.So while they do not play a role in preventing one container
  ```