NLB: Configure Site Sync between two load balanced environments

1. Set up the project on the two or more servers to point to the same source database.
2. Do a test ping from one server to the rest and ensure it is successful.
3. Generate an ASP.NET 2.0 Machine Key.
   Use an ASP.NET Machine Key Generator, such as http://www.developerfusion.com/tools/generatemachinekey/
4. For all of the servers of the source environment, perform the following:
   1. Open the web.config file and find the <system.web> element that is directly under the <configuration> element – not the one under a <location> element.
   2. Place the copied ASP.NET 2.0 Machine Key directly under the <system.web> element. 
      Use the same machine key.
5. For all of the servers of the source environment, perform the following:
   1. Browse the site explicitly.
   2. Log in to the backend and navigate to Administration » Settings » Advanced » System » LoadBalancing » WebServerUrls
   3. Create new entries with the IP addresses of all of the rest of the servers. 
      Use the IP address. For example, http://199.166.0.1/
6. Restart all nodes of the source environment at the same time.
   Without browsing the sites, open the web.config files of all nodes and resave them.
7. Test the load balancing to ensure it works correctly.
   1. Browse a frontend page of the site on one of the servers two or three times to ensure it is served from output cache.
   2. Log in to the backend of one of the sites, make a change to the page and publish it.
   3. Refresh the page on another server and check if the change appears.

NOTE: You can optionally configure a load balancer that distributes the traffic between the nodes.

To configure SiteSync on between a Sitefinity website environments running in Load Balanced setup follow the instructions on the Specifics when configuring SiteSync in load balanced setup article.