I have run across the situation a few times where I needed to reset secure channel for the computer account of a domain controller.  Before I get into how to do this, let me present a few of  the symptoms that would require resetting secure channel.

1. You receive an access denied error when access the DNS management console on the problem domain controller.
2. You run nltest /sc_query:domain.local and receive access denied.
3. You run nltest /sc_verify:domain.local and receive access denied.

Here is how you reset secure channel on a domain controller:

1. Open an administrative command line
2. Run the following commands*:
   • net stop kdc
   • klist purge
   • netdom resetpwd /server:<DCName> /userD:<domain\username> /passwordD:*
   • net start kdc
   • net stop DNS & net start DNS

*In the netdom resetpwd command replace <DCName> with the name of a peer DC, or in the case of a single domain controller, the server  itself.