Active directory users and computers wont start on a dc, "the server is not operational"

Question

In our environment, we have 3 dc's 
two which run server 2008 (they work perfectly)
and one never off branch dc that runs server 2008 r2.
We have been having some problems where we feel the replication isnt up too speed(stuff could take up to 24 hours to replicate) and now when i tried opening active directory users and computers i am met with this error window:
We have a third party DNS solution.
How do i troubleshoot this issue?

Answer 1

dc01 (which replicates perfectly with dc02, and vise versa)
dcdiag /test:dns
C:\Users\adminuser>dcdiag /test:dns
Domain Controller Diagnosis
Performing initial setup:
Done gathering initial info.
Doing initial required tests
Testing server: Hostingpartner\ourdc01
Starting test: Connectivity
......................... ourDC01 passed test Connectivity
Doing primary tests
Testing server: Hostingpartner\ourdc01
DNS Tests are running and not hung. Please wait a few minutes...
Running partition tests on : ForestDnsZones
Running partition tests on : DomainDnsZones
Running partition tests on : Schema
Running partition tests on : Configuration
Running partition tests on : int
Running enterprise tests on : int.domain.com
Starting test: DNS
Test results for domain controllers:
DC: ourdc01.int.domain.com
Domain: int.domain.com
TEST: Delegations (Del)
Error: DNS server: ourdc02.int.domain.com. IP:xx.xx.xx.32 [Broken delegated domain domaindnszones.int.domain.com.]
Error: DNS server: ourdc02.int.domain.com. IP:xx.xx.xx.32 [Broken delegated domain forestdnszones.int.domain.com.]
Summary of test results for DNS servers used by the above domain controllers:
DNS server: xx.xx.xx.32 (ourdc02.int.domain.com.)
2 test failures on this DNS server
Delegation is broken for the domain domaindnszones.int.domain.com. on the DNS server xx.xx.xx.32
Delegation is broken for the domain forestdnszones.int.domain.com. on the DNS server xx.xx.xx.32
Summary of DNS test results:
Auth Basc Forw Del Dyn RReg Ext
Domain: int.domain.com
ourdc01 PASS PASS PASS FAIL n/a PASS n/a
......................... int.domain.com failed test DNS
dcdiag on dc01(which can replicate with dc02)
C:\Users\adminuser>dcdiag
Domain Controller Diagnosis
Performing initial setup:
Done gathering initial info.
Doing initial required tests
Testing server: hostingpartner\ourdc01
Starting test: Connectivity
......................... OURDC01 passed test Connectivity
Doing primary tests
Testing server: hostingpartner\ourdc01
Starting test: Replications
[Replications Check,OURDC01] DsReplicaGetInfoW(PENDING_OPS) failed with error 8453,
Win32 Error 8453.
......................... OURDC01 failed test Replications
Starting test: NCSecDesc
......................... OURDC01 passed test NCSecDesc
Starting test: NetLogons
[OURDC01] User credentials does not have permission to perform this operation.
The account used for this test must have network logon privileges
for this machine's domain.
......................... OURDC01 failed test NetLogons
Starting test: Advertising
......................... OURDC01 passed test Advertising
Starting test: KnowsOfRoleHolders
......................... OURDC01 passed test KnowsOfRoleHolders
Starting test: RidManager
......................... OURDC01 passed test RidManager
Starting test: MachineAccount
......................... OURDC01 passed test MachineAccount
Starting test: Services
......................... OURDC01 passed test Services
Starting test: ObjectsReplicated
......................... OURDC01 passed test ObjectsReplicated
Starting test: frssysvol
......................... OURDC01 passed test frssysvol
Starting test: frsevent
......................... OURDC01 passed test frsevent
Starting test: kccevent
......................... OURDC01 passed test kccevent
Starting test: systemlog
An Error Event occured. EventID: 0xC0002719
Time Generated: 04/04/2013 15:04:29
(Event String could not be retrieved)
An Error Event occured. EventID: 0xC0002719
Time Generated: 04/04/2013 15:04:50
(Event String could not be retrieved)
An Error Event occured. EventID: 0xC0002719
Time Generated: 04/04/2013 15:10:56
(Event String could not be retrieved)
An Error Event occured. EventID: 0xC0002719
Time Generated: 04/04/2013 15:11:17
(Event String could not be retrieved)
......................... OURDC01 failed test systemlog
Starting test: VerifyReferences
......................... OURDC01 passed test VerifyReferences
Running partition tests on : ForestDnsZones
Starting test: CrossRefValidation
......................... ForestDnsZones passed test CrossRefValidation
Starting test: CheckSDRefDom
......................... ForestDnsZones passed test CheckSDRefDom
Running partition tests on : DomainDnsZones
Starting test: CrossRefValidation
......................... DomainDnsZones passed test CrossRefValidation
Starting test: CheckSDRefDom
......................... DomainDnsZones passed test CheckSDRefDom
Running partition tests on : Schema
Starting test: CrossRefValidation
......................... Schema passed test CrossRefValidation
Starting test: CheckSDRefDom
......................... Schema passed test CheckSDRefDom
Running partition tests on : Configuration
Starting test: CrossRefValidation
......................... Configuration passed test CrossRefValidation
Starting test: CheckSDRefDom
......................... Configuration passed test CheckSDRefDom
Running partition tests on : int
Starting test: CrossRefValidation
......................... int passed test CrossRefValidation
Starting test: CheckSDRefDom
......................... int passed test CheckSDRefDom
Running enterprise tests on : int.domain.com
Starting test: Intersite
......................... int.domain.com passed test Intersite
Starting test: FsmoCheck
......................... int.domain.com passed test FsmoCheck
The problematic dc03:
Dcdiag gives the same output as dcdiag /test:dns
C:\Users\adminuser>dcdiag
Directory Server Diagnosis
Performing initial setup:
Trying to find home server...
Home Server = OURDC03
Ldap search capabality attribute search failed on server NTSDC03, return
value = 81
We have an infoblox dns server on ip address xxx.y.y.251.
first error in event logs on dc03:
error 1863
This is the replication status for the following directory partition on this directory server.
Directory partition:
CN=Configuration,DC=int,DC=domain,DC=com
This directory server has not received replication information from a number of directory servers within the configured latency interval.
Latency Interval (Hours):
24
Number of directory servers in all sites:
2
Number of directory servers in this site:
2
The latency interval can be modified with the following registry key.
Registry Key:
HKLM\System\CurrentControlSet\Services\NTDS\Parameters\Replicator latency error interval (hours)
To identify the directory servers by name, use the dcdiag.exe tool.
You can also use the support tool repadmin.exe to display the replication latencies of the directory servers. The command is "repadmin /showvector /latency <partition-dn>".
i have also go several warning 2088, 2093, 2087.
And errors 1863 pointing to different directory partitions like schema/configuration/domaindnszones/forestdnszones