text: 19th February 2008, 07:40
  In our network there are 2 Domain controller (both are same), i mean we have additional domain controller for failure redundancy. my question is: if first dc will down, what should i do for set additional dc as main domain controller and our users use it for authentication? if there are pre-actions for this situation please help me step-by-step.
  Amir Ahmadi Rad
  Jamsaz co.
  19th February 2008, 09:58
  As long as your second DC is a global catalogue (http://www.petri.com/configure_a_new_global_catalog.htm) you shouldn't have to do anything. You may have issues with resetting users passwords depending on which server is your PDC emulator:
  25th February 2008, 06:34
  Dear m80arm
  Thanks for your attention. 2 days ago in Network Lab i tested some situation. i configured two DC . one with 5 roles and GC & another just GC.based on my knowledge 2nd DC couldn't response to user authentication without DC1 unless that it has PDC Emulator master role and GC. i down DC1 and Sieze all (5) roles to DC2.everythings ok. all users could logon to Domain. but there is an isuue, if i start DC1 again what happend? there are 2 DC that both of them have 5 roles. as you know in a forest there is just one DC that can hold Schema master role & Domain Naming Master. and in any Domain there is just one DC can hold PDC Emulator, Infrastructure and RID master roles.Please help me. What should i do in this Situation? How can i remove 5 roles in DC2?[/CENTER][/LEFT][/CENTER][/RIGHT]
  25th February 2008, 09:02
  In the real world you should never start a DC that's had any FSMO role seized from it. You never know what could happen.
  the PDC emulator should only be contacted when a users password has been reset. DC2 should authenticate users if it was a DC and a GC. I would check to ensure DC2 is definately replication from DC1. Check the event logs etc