What is the relationship between Exchange Server and PDC Emulator role? When PDC server down, does Exchange and outlook client work healtly? Is it possible outlook connection lost in this scenerio? how long works correctly? Is there a time limit for sizing this role? All about my asking just for Exchange Server.

The PDC Emulator is responsible of keeping the time synchronized on all the DCs --- Once you lose the Time sync between DC"s You might face Drastic issues with your Calendar. Free busy etc. --- Client will connect without any issues Its again depends on your env. Once the DC;s lose time sync. replication may stop working , End result differs --- There is no specific Time we can define when the problem will start over --- Satheshwaran Manoharan | Exchange 2003/2007/2010 | Blog:http://www.careexchange.in | Please mark it as an answer if it really helps you