anchor.diff:  
   <p class="note"><b>Note:</b> Always use an odd number of AZs. This ensures that your deployment remains available when greater than half of the AZs are available. For example, a deployment with three AZs stays available when one AZ goes down and two AZs are still available.</p>
   
  -## <a id='external-lbs'></a> External Load Balancers for High Availability
  +### <a id='external-lbs'></a> External Load Balancers
   
   External load balancers distribute traffic coming from the internet to your internal network. 
   
  
positive.code: For more information about scaling applications and maintaining app uptime, see the following topics:
  
  * [Scaling an Application Using cf scale](../devguide/deploy-apps/cf-scale.html)
  *[Using Blue-Green Deployment to Reduce Downtime and Risk](../devguide/deploy-apps/blue-green.html).
  
  ### <a id='vert-scaling'></a> Scale Vertically
  
  
negative.code: 
  <%= vars.external_lb %>
  
  ### <a id='blobstore'></a> External Blob Storage
  
  Blobs are large binary files. To store blobs for high availability, use external storage such as Amazon S3 or an S3-compatible service. 
  
  