Following are the points you can consider while troubleshooting with Citrix XenDesktop 5.x versions:
- Firewall configuration: Not only Windows firewall but any other firewall like McAfee or Symantec or others might block the communication. The easiest way to check is to telnet VDA from DDC and vice versa.
- DNS not configured properly: For the unregistered VDA, try to do forward lookup as well as reverse lookup. Do ping to it and compare it with ipconfig output. You can also try nslookup queries or other custom script if available.
- Time synchronization: This is very important place to look because Kerberos is being used where default Kerberos setting accepts 5 minutes difference.
- Domain membership: This could be least likely place to look but its worth checking, specially where multiple domains or sub-domains exist.
- Multiple NICs: Multiple NICs may cause a communication negotiation to fail.
- Service Principal Names (SPNs): A service principal name (SPN) is a unique identifier of a service instance. SPNs are used by Kerberos authentication to associate a service instance with a service logon account. This allows a client application to request that the service authenticate an account even if the client does not have the account name. So this is very important during VDA registration process where Controller will have a look at AD object of the VDA and automatically determine SPN by inspecting servicePrincipalName attribute.
- Proper DDC not found: This is quite a common mistake while setting up the VDA installer.
- Operation timed out: XenDesktop brokering is based on Windows Communication Foundation where activities may have timeouts which could reflect on the events. Increasing the timeout option may be available but it’s strongly recommended to trace the communication flow through WireShark or WCF Trace (https://msdn.microsoft.com/en-us/library/aa751795(v=vs.110).aspx).
- MTU settings: Check if the default MTU is 1500 or not.
- Use XDPing: http://support.citrix.com/article/CTX123278
- Other causes: http://support.citrix.com/article/CTX117449