title: How many number of hosts do IP classes A, B, and C have?
body: <p>I don't under stand this so please someone help correct my view.</p>
  
  <pre><code>Class     First Byte Order      Number of Hosts
  A         0 - 127               256 * 256 * 256
  B         128 - 191             256 * 256
  C         192 - 223             256
  </code></pre>
  
  <p>I don't under stand why Class B and C have less number of hosts? To me it seems that if the first byte order is defined above, then we should get roughly the following numbers of permutations for IP</p>
  
  <pre><code>Class     Permutations
  A         128 * 256^3
  B         63 * 256^3      
  C         31 * 256^3
  </code></pre>
  
  <p>I'm understanding this as the last three bytes of IP (0.XXX.XXX.XXX) can be non unique between the 3 IP classes as long as the first byte order has a unique range where the classes don't intersect. </p>
  
  <p>What's wrong with my understand?</p>