Question : DCDIAG returns Directory Binding Error 1726 - DNS Issue?

Hi everyone, I am running Win2K3 SP2 with 2 DC's on one subnet and the PDC running Exchange 2003, ISA 2004 and IIS 6 and am getting persistent errors on the PDC that seem to be DNS related. Black box to me.

DCDIAG returns the following issues:

Connecting to AD - Directory Binding Error 1726:  The remote procedure call failed.

RPC Services Check - DsBindWithSpnEx() failed with error 1726, The remote procedure call failed.. also error -1073606647.

FsmoCheck - Warning: Couldn't verify this server as a PDC using DsListRoles()

Here is the ipconfig/all config:
Windows IP Configuration
   Host Name . . . . . . . . . . . . : aguirre
   Primary Dns Suffix  . . . . . . . : amazonia.com
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : Yes
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : amazonia.com

Ethernet adapter External NIC:
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Broadcom BCM5708C NetXtreme II GigE (NDIS
 VBD Client)
   Physical Address. . . . . . . . . :
   DHCP Enabled. . . . . . . . . . . : No
   IP Address. . . . . . . . . . . . : 70.91.104.193
   Subnet Mask . . . . . . . . . . . : 255.255.255.252
   Default Gateway . . . . . . . . . : 70.91.104.194
   DNS Servers . . . . . . . . . . . : 68.87.68.162
                                       68.87.74.162
   NetBIOS over Tcpip. . . . . . . . : Disabled

Ethernet adapter Internal NIC:
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Broadcom BCM5708C NetXtreme II GigE (NDIS
 VBD Client) #2
   Physical Address. . . . . . . . . :
   DHCP Enabled. . . . . . . . . . . : No
   IP Address. . . . . . . . . . . . : 192.168.254.11
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :
   DNS Servers . . . . . . . . . . . : 192.168.254.11
   Primary WINS Server . . . . . . . : 192.168.254.11

Any pointers would ge greatly appreciated. TIA

Answer : DCDIAG returns Directory Binding Error 1726 - DNS Issue?

Just to be honest, idealy you would not have the DC and Exchange server running on the ISA server. If it were me I would have a seperate ISA server, a DC running DNS and DHCP, and then a seperate Exchange server. I know that you probably won't be able to reconfigure it in this way as it is a production network, but in the future it may be something for you to think about... just my $.02.

Just to confirm though...

(1) All IP addresses are assigned statically.
(2) The external NIC of the ISA server has no DNS information
(3) The internal NIC of the ISA server points towards itself for DNS (127.0.0.1), clear other DNS entries.
(4) The NIC in the second DC points towards itself for DNS (127.0.0.1), clear other DNS entries.
(5) In the DNS properties on the second DC, forwarders are set to first forward to DC #1, then to the IPs of your ISP's DNS servers.
(6) In the DNS properties on the first DC, forwarders are set to forward the to IPs of your ISP's DNS servers.

I know we have gone through this, but I would like you to do the following again:

(1) On the first DC, run an IPCONFIG /REGISTERDNS. After 5 minutes, restart the DC. Wait for it to come back up.
(2) On the second DC, run an IPCONFIG /REGISTERDNS. After 5 minutes, restart the DC. Wait for it to come back up.
(3) Run a NETDIAG /FIX on the first DC. Post the results.
(4) Run a DCDIAG on the first DC. Post the results.

Sorry we haven't come to a resolution yet, but I will continue to work with you.