title: Cannot start rabbitmq, 'node down' Ubuntu 16.04
body: <p>Similar to <a href="https://stackoverflow.com/questions/28258392/rabbitmq-has-nodedown-error">RabbitMQ has Nodedown Error</a>. But, this is for Ubuntu 16.04 the working solution, posted below, differs from the windows one as well. </p>
  
  <p>Something has gone wrong with my rabbitmq server. Trying to start the application gives an error:</p>
  
  <pre><code>$sudo rabbitmqctl start_app
  
  Starting node rabbit@daniel ...
  Error: unable to connect to node rabbit@daniel: nodedown
  
  DIAGNOSTICS
  ===========
  
  attempted to contact: [rabbit@daniel]
  
  rabbit@daniel:
    * connected to epmd (port 4369) on daniel
    * epmd reports: node 'rabbit' not running at all
                    no other nodes on daniel
    * suggestion: start the node
  
  current node details:
  - node name: 'rabbitmq-cli-6647@daniel'
  - home dir: /var/lib/rabbitmq
  - cookie hash: T1R4ztWXXH1w2IQe+fui9g==
  </code></pre>
  
  <p>Currently the only way I know of solving this is uninstalling/reinstalling rabbitmq. But, I'm hoping a more sensible solution is possible...</p>