title: React-Router 4 catch all route
body: <p>My React routes are defined as follows:</p>
  
  <pre><code>...
  &lt;Route component={Header} /&gt;
  &lt;Route exact path="/" component={Landing} /&gt;
  &lt;Route path="/about" component={About} /&gt;
  &lt;Route path="/contact" component={Contact} /&gt;
  &lt;Route component={Footer} /&gt;
  ...
  </code></pre>
  
  <p>I want to define a catch all route that catches anything that does not match the Landing, About or Contact routes, and instead redirects to a 404 Not found page. How can I do it with React Router 4?</p>