If I run repadmin /replsum I get rpc service unavailable, but if I reboot the servers with the RPC errors then repadmin /replsum works fine. I have forest level 2008 R2 with Windows Server 2008 R2, Windows 2012 core and Windows 2012 R2 servers running as DCs in five different locations and different subnets.

I would recommend that you start with that especially the IP setting recommendations: http://www.ahmedmalek.com/web/fr/articles.asp?artid=23

I also recommend that you dcdiag to check that your DCs are in healthy state.

See also that: https://social.technet.microsoft.com/Forums/windowsserver/en-US/8b62cd08-65c1-49e7-9919-881f6ff5a105/the-rpc-server-is-unavailableerror-1722?forum=winserverDS

You might want to temporary disable security software running on your DCs for te

Hi,

I would agree with Ahmed MALEK.

RPC error 1722 / 0x6ba / RPC_S_SERVER_UNAVAILABLE is logged when a lower layer protocol reports a connectivity failure. The common case is that the abstract TCP CONNECT operation failed. In the context of AD replication, the RPC client on the destination DC was not able to successfully connect to the RPC server on the source DC.

Troubleshooting AD Replication error 1722: The RPC server is unavailable

https://support.microsoft.com/en-us/kb/2102154

Please try the suggestions, feel free to let us know if you need further assistance.

Regards.

Hello,

in addition assure that firewalls between DCsare open according to https://technet.microsoft.com/en-us/library/dd772723(WS.10).aspx

Hi,

I just want to confirm what is the current situation.

Please feel free to let us know if you need further assistance.

Regards.

I folllowed http://www.ahmedmalek.com/web/fr/articles.asp?artid=23, but continue to get 1722 errors when I run repadmin /replsum.

I've attached the results from my dcdiag are below, but nothing jumps out at me. Any ideas?

Directory Server Diagnosis


Performing initial setup:

   Trying to find home server...

   Home Server = TEMPUS

   * Identified AD Forest. 
   Done gathering initial info.


Doing initial required tests

   
   Testing server: Default-First-Site-Name\TEMPUS

      Starting test: Connectivity

         ......................... TEMPUS passed test Connectivity



Doing primary tests

   
   Testing server: Default-First-Site-Name\TEMPUS

      Starting test: Advertising

         ......................... TEMPUS passed test Advertising

      Starting test: FrsEvent

         ......................... TEMPUS passed test FrsEvent

      Starting test: DFSREvent

         ......................... TEMPUS passed test DFSREvent

      Starting test: SysVolCheck

         ......................... TEMPUS passed test SysVolCheck

      Starting test: KccEvent

         ......................... TEMPUS passed test KccEvent

      Starting test: KnowsOfRoleHolders

         ......................... TEMPUS passed test KnowsOfRoleHolders

      Starting test: MachineAccount

         ......................... TEMPUS passed test MachineAccount

      Starting test: NCSecDesc

         ......................... TEMPUS passed test NCSecDesc

      Starting test: NetLogons

         ......................... TEMPUS passed test NetLogons

      Starting test: ObjectsReplicated

         ......................... TEMPUS passed test ObjectsReplicated

      Starting test: Replications

         [Replications Check,TEMPUS] A recent replication attempt failed:

            From SCCM-HOUSTON to TEMPUS

            Naming Context: DC=DomainDnsZones,DC=Advocacyinc,DC=org

            The replication generated an error (1256):

            The remote system is not available. For information about network troubleshooting, see Windows Help.

            

            The failure occurred at 2015-03-22 19:47:46.

            The last success occurred at 2015-03-22 19:33:29.

            1 failures have occurred since the last success.

         [Replications Check,TEMPUS] A recent replication attempt failed:

            From SCCM-HOUSTON to TEMPUS

            Naming Context: DC=ForestDnsZones,DC=Advocacyinc,DC=org

            The replication generated an error (1256):

            The remote system is not available. For information about network troubleshooting, see Windows Help.

            

            The failure occurred at 2015-03-22 19:47:46.

            The last success occurred at 2015-03-22 19:33:29.

            1 failures have occurred since the last success.

         [Replications Check,TEMPUS] A recent replication attempt failed:

            From SCCM-HOUSTON to TEMPUS

            Naming Context: CN=Schema,CN=Configuration,DC=Advocacyinc,DC=org

            The replication generated an error (1722):

            The RPC server is unavailable.

            The failure occurred at 2015-03-22 19:48:07.

            The last success occurred at 2015-03-22 19:33:29.

            1 failures have occurred since the last success.

            The source SCCM-HOUSTON is responding now.

         [Replications Check,TEMPUS] A recent replication attempt failed:

            From SCCM-HOUSTON to TEMPUS

            Naming Context: CN=Configuration,DC=Advocacyinc,DC=org

            The replication generated an error (1722):

            The RPC server is unavailable.

            The failure occurred at 2015-03-22 19:47:46.

            The last success occurred at 2015-03-22 19:33:07.

            1 failures have occurred since the last success.

            The source SCCM-HOUSTON is responding now.

         [Replications Check,TEMPUS] A recent replication attempt failed:

            From SCCM-HOUSTON to TEMPUS

            Naming Context: DC=Advocacyinc,DC=org

            The replication generated an error (1722):

            The RPC server is unavailable.

            The failure occurred at 2015-03-22 19:48:28.

            The last success occurred at 2015-03-22 19:33:29.

            1 failures have occurred since the last success.

            The source SCCM-HOUSTON is responding now.

         ......................... TEMPUS failed test Replications

      Starting test: RidManager

         ......................... TEMPUS passed test RidManager

      Starting test: Services

         ......................... TEMPUS passed test Services

      Starting test: SystemLog

         ......................... TEMPUS passed test SystemLog

      Starting test: VerifyReferences

         ......................... TEMPUS passed test VerifyReferences

   
   
   Running partition tests on : DomainDnsZones

      Starting test: CheckSDRefDom

         ......................... DomainDnsZones passed test CheckSDRefDom

      Starting test: CrossRefValidation

         ......................... DomainDnsZones passed test

         CrossRefValidation

   
   Running partition tests on : ForestDnsZones

      Starting test: CheckSDRefDom

         ......................... ForestDnsZones passed test CheckSDRefDom

      Starting test: CrossRefValidation

         ......................... ForestDnsZones passed test

         CrossRefValidation

   
   Running partition tests on : Schema

      Starting test: CheckSDRefDom

         ......................... Schema passed test CheckSDRefDom

      Starting test: CrossRefValidation

         ......................... Schema passed test CrossRefValidation

   
   Running partition tests on : Configuration

      Starting test: CheckSDRefDom

         ......................... Configuration passed test CheckSDRefDom

      Starting test: CrossRefValidation

         ......................... Configuration passed test CrossRefValidation

   
   Running partition tests on : Advocacyinc

      Starting test: CheckSDRefDom

         ......................... Advocacyinc passed test CheckSDRefDom

      Starting test: CrossRefValidation

         ......................... Advocacyinc passed test CrossRefValidation

   
   Running enterprise tests on : Advocacyinc.org

      Starting test: LocatorCheck

         ......................... Advocacyinc.org passed test LocatorCheck

      Starting test: Intersite

         ......................... Advocacyinc.org passed test Intersite

Hi,

Sorry for the delay reply.

So did you refer to the following MS KB article to check the result?

Troubleshooting AD Replication error 1722: The RPC server is unavailable

https://support.microsoft.com/en-us/kb/210215

Regards.

Hi,

Any update about the issue?

Regards.

Still having same issue.

Hi,

I have saw the replication error 1256.

When the destination DC fails to bind to the source DC using RPC, a win32 error code appears in the Repsfrom status for that partition - usually Schema or Configuration partitions because they are replicated at a higher priority. After an RPC bind failure has occurred, a cleanup routine will run to clear the destination DCs queue from that same source DC.

Did you refer to this MS article?

Replication error 1256 The remote system is not available

https://technet.microsoft.com/en-us/library/replication-error-1256-the-remote-system-is-not-available(v=ws.10).aspx

Regards.

I did. When I run repadmin /showreps I get no errors.

When I try to manually replicate between two DCs that are having problems I get:

DsReplicaSync() failed with status 8452 (0x2104):
    The naming context is in the process of being removed or is not replicated f
rom the specified server.

Hi,

DsReplicaSync() failed with status 8452 (0x2104)

This error most commonly occurs when replication topology on a domain controller that initiates replication differs from the replication topology defined on the copy of Active Directory on the destination domain controller.

https://technet.microsoft.com/en-us/library/replication-error-8452-the-naming-context-is-in-the-process-of-being-removed-or-is-not-replicated-from-the-specified-server%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396

Regards.

This is resolved. I had two NICs on some of my DCs which was causing the problem. As soon as I disabled the second NIC on each DC I didn't get anymore 1722 errors.

• Marked as answer by Carltonw1 17 hours 40 minutes ago

This is resolved. I had two NICs on some of my DCs which was causing the problem. As soon as I disabled the second NIC on each DC I didn't get anymore 1722 errors.

Hello,

DCs should NOT use more then one NIC. And if you team NICs then assure that they a re NOT configured for load balancing as this is not supported.

Hi,

Glad the issue was solved by yourself.

As mvp mentioned, multihoming DCs should be avoided for multiple reasons.

A Multihomed DC is a domain controller with more than one NIC and/or IP address, and/or RRAS installed on it (for VPN, routing, dialup, etc), or with a PPPoE adapter from your ISPs ADSL line.

http://blogs.msmvps.com/acefekay/2009/08/17/multihomed-dcs-with-dns-rras-and-or-pppoe-adapters/

Regards.