I see you going 2008 64 bit which I think you would be going to XenApp 6 on this. See also http://blogs.citrix.com/2010/09/28/a-mixed-farm-consisting-of-xenapp-5-a nd-6/ From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Angela Smith Sent: 09 August 2011 09:23 To: thin@xxxxxxxxxxxxx Subject: [THIN] Mixed Windows OS's in 1 farm? Hi My current farm comprises of Windows 2003 R2 (x86) running XenApp 4.5. I need to add a Windows 2008 (x64) server to my existing Citrix farm. Are there any issues with mixing OS versions??? The Windows 2008 server will only be used to publish a single application. Will the 2008 server become a preferred ZDC due to newer OS version or can I safely mix OS's? Thanks Ang Visit our website : www.ltai.ie __________________________________________ Lufthansa Technik Airmotive Ireland Limited. Registered in Ireland. Reg. No. 45999. Registered Office: Naas Road, Rathcoole, Co.Dublin. Lufthansa Technik Airmotive Ireland Leasing Limited. Registered in Ireland. Reg. No. 140891. Registered Office: Naas Road, Rathcoole, Co.Dublin. __________________________________________ The information in this email and in any attachments is confidential and may be privileged. If you are not the intended recipient, please destroy this message, delete any copies held on your systems and notify the sender by return email. You should not read, retain, copy, disseminate, distribute, disclose or use this email or its contents in any way. Any such action is strictly prohibited. Thank you.