For my 1Y0-A20 XenApp 6.5 administration exam I’ve used a lot of knowledge base articles and other resources besides the self paced online course (courtesy of my employer).
This is a great document which shows all ports used by all Citrix products. Not only useful for an exam but also for troubleshooting purposes.
Go through the free XenApp 6.5 overview training from Citrix Education and read the 1Y0-A20 Preparation Guide from Citrix.
Here are the most useful kb articles and other free online resources I used to prepare for this exam.
1. Printing
How to replicate printer drivers
2. Policies
3. Tools
How to use Print detective tool
PNP util printer driver utility
How to use stress printers tool
4. HDX
HDX mediastream flash redirection server side
Enable server side content fetching in HDX mediastream for flash
Configuring HDX mediastream flash redirection
5. Profile management
Cross platform profile management FAQ
6. Application streaming / profiles and launching
Reduce application launch time
Session pre-launch field guide
Decide which plugin to use for application streaming
Create application profile and target
7. Access gateway / Web interface
Error when launching applications through Access Gateway or Web Interface
Password settings prompt authententication
Configure two factor authentication
8. Worker groups
9. Session sharing
Troubleshooting and explaning session sharing
10. Content redirection
11. Workspace control
Configure workspace control settings
12. Logon restrictions / reboot
Enable or deny logons to servers
13. Database options
14. Load evaluators
15. Monitoring
Performance monitoring using health monitor
How to create a Health Monitoring and Recovery policy for XenApp version 6.0 and later
16. Speedscreen / image compression
Image acceleration using lossy compression
Optimizing mouse and keyboard responsiveness
17. Licensing
How to upgrade license server to version 11.10
18. Planning server functions
Configure zones and backup controllers