KMS activation not automatic

Question

Hi all,
In my company, there is a kms server in a domain :Domain1. Any joined member server activate automaticaly.
The DNS suffix of this domain is Domain1.company.net
I' m trying to know how KMS activation works for server in workgroup or in another domain.
So
I installed a Windows 2012R2 server using a volume ISO. After installation, the server is not activated. OK
I do not enter any key
The DNS servers configured here are not the DNS servers of Domain1
Then, I add the dns suffix Domain1.company.net in the network configuration. This  way,
nslookup -type=srv _vlmcs._tcp returns : 
PS C:\Users\Administrator> nslookup -type=srv _vlmcs._tcp
Server:  another.domain.net
Address:  xxx.xxx.xxx.xxx Non-authoritative answer:
_vlmcs._tcp.domain1.company.net    SRV service location:
          priority       = 0
          weight         = 0
          port           = 1688
          svr hostname   = kmsserver.Domain1.company.net
kmsserver.Domain1.company.net       internet address = aaa.bbb.ccc.ddd
I thought this way, the new installed server should activate automaticaly within 2 hours. But it don't. I wonder why ?
If I enterslmgr /ato. The activation work fine.
There is no firewall between my installed server and the KMS server.
BTW, could you confirm that the 2012R2 server must be able to contact the kms server at least every 180 days ?
I ask because some workgroup servers are behind very restricted firewalls in dedicated networks.
If they can't reach a KMS, do a phone activation for theses servers could make it without kms request every 180 days ? Or we must open the TCP port 1688 to the kms server for each of them ?
Thank you.
ML
ML

Answer 1

Hi ML,
To activate clients across domains via KMS server, please follow these steps to create KMS server SRV record on the other DNS domain:
Here is the procedure in order to create the SRV record in the other DNS domain that publishes the availability of a remote KMS host -
1.On the DNS server, open DNS Manager. To open DNS Manager, click Start, click Administrative Tools, and then click DNS.
2.Click the DNS server on which you need to create the SRV resource record.
3.In the console tree, expand Forward Lookup Zones, right-click the domain, and then click Other New Records.
4.Scroll down the list, click Service Location (SRV), and then click Create Record.
5.Type the following information: a.Service: _VLMCS
b.Protocol: _TCP
c.Port number: 1688
d.Host offering the service:<FQDN_of_KMS_Host>
6.When you are finished, click OK, and then click Done.
Then check if the server can be activated automatically.
Refer to:
Using Key Management Services (KMS) Across Domains
If the steps above also can't work, please also refer to the steps in this article:
KMS Activation
And yes, KMS activations are valid for 180 days—the activation validity interval. To remain activated, KMS client computers must renew their activation by connecting to the KMS host at least once every 180 days.
If you want to activate client via MAK like phone:
Pro:  It is activated permanently. It does not need to reactivate on any pre-set interval.
Con: You must enter a product key each time you set up a new workstation or server. Operating systems will not activate automatically.
Con: Each MAK key has a limited number of activations. (You still may be able to activate more computers than licensed. You are responsible for maintaining records of your licensing compliance.)
Con: Hardware changes may invalidate your activation. If your MAK key's activation count is depleted, reactivating will require a phone call to Microsoft.
Refer to:
Activating Windows 7: KMS vs. MAK
If there is anything else regarding this issue, please feel free to post back.
Best Regards,
Anna Wang