Unable to connect to AD Users & Computers - DC (Win2016)

Question

Dears,

I'm unable to connect to AD Users & Computers from the DC (we only have single instance of DC).
Also can't connect to AD Sites & Services.

Below is the error that's coming:
Naming information cannot be located because: The specified domain either does not exist or could not be contacted.

If I try to change the Domain Controller at AD Users & Computers or Site & Services I get the error: The following Domain Controller cannot be contacted: x.x.x.x

The DNS services are working fine & the DNS records are fine.

Below is output of dcdiag:

C:\Windows\system32>dcdiag

Directory Server Diagnosis

Performing initial setup:
Trying to find home server...
Home Server = HCS-MGMT-DC-01
* Identified AD Forest.
Done gathering initial info.

Doing initial required tests

Testing server: Default-First-Site-Name\HCS-MGMT-DC-01
Starting test: Connectivity
An error that is usually temporary occurred during DNS host lookup. Please try again later.
Got error while checking LDAP and RPC connectivity. Please check your firewall settings.
......................... HCS-MGMT-DC-01 failed test Connectivity

Doing primary tests

Testing server: Default-First-Site-Name\HCS-MGMT-DC-01
Skipping all tests, because server HCS-MGMT-DC-01 is not responding to directory service requests.

Running partition tests on : ForestDnsZones
Starting test: CheckSDRefDom
......................... ForestDnsZones passed test CheckSDRefDom
Starting test: CrossRefValidation
......................... ForestDnsZones passed test CrossRefValidation

Running partition tests on : DomainDnsZones
Starting test: CheckSDRefDom
......................... DomainDnsZones passed test CheckSDRefDom
Starting test: CrossRefValidation
......................... DomainDnsZones 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 : HCS-COMPANY
Starting test: CheckSDRefDom
......................... HCS-STCS passed test CheckSDRefDom
Starting test: CrossRefValidation
......................... HCS-STCS passed test CrossRefValidation

Running enterprise tests on : HCS-COMPANY.Local
Starting test: LocatorCheck
Warning: DcGetDcName(GC_SERVER_REQUIRED) call failed, error 1355
A Global Catalog Server could not be located - All GC's are down.
Warning: DcGetDcName(TIME_SERVER) call failed, error 1355
A Time Server could not be located.
The server holding the PDC role is down.
Warning: DcGetDcName(GOOD_TIME_SERVER_PREFERRED) call failed, error 1355
A Good Time Server could not be located.
Warning: DcGetDcName(KDC_REQUIRED) call failed, error 1355
A KDC could not be located - All the KDCs are down.
......................... HCS-COMPANY.Local failed test LocatorCheck
Starting test: Intersite
......................... HCS-COMPANY.Local passed test Intersite

C:\Windows\system32>

Answer 1

![148223-screenshot-at-nov-10-16-27-29.png][1] [1]: /api/attachments/148223-screenshot-at-nov-10-16-27-29.png?platform=QnA This fixed the issue.

Answer 2

If I try to change the Domain Controller at AD Users & Computers or Site & Services

What are you changing it to? you mentioned a single DC.

I'd check the server has own static ip address listed for DNS plus loop back (127.0.0.1) and no others such as router or public DNS. Also check the windows time service is running.

--please don't forget to upvote and if the reply is helpful--

Answer 3

Hi DSPatrick,

Yes, it's a single DC.
When I right click on AD Users & Sites, I see 2 options Change Domain or Change Domain Controller, so I was trying by selecting Change Domain Controller setting to see if it works.

Yes, confirmed server has its own static IP Address for DNS, already checked this.
Windows time service is also working and time is correct.

Answer 4

so I was trying by selecting Change Domain Controller setting to see if it works.

Doesn't make sense, what would you change it to? Please run;

Dcdiag /v /c /d /e /s:%computername% >C:\dcdiag.log
repadmin /showrepl >C:\repl.txt
ipconfig /all > C:\dc1.txt
ipconfig /all > C:\dc2.txt

then put unzipped text files up on OneDrive and share a link.

Answer 5

What's the history here? What events led up to this? About the firewall I'd check that it got the domain network profile and if not try restarting the Network Location Awareness service