The KMS client then initializes a connection to port 1688 on the KMS server.īy default, a Windows installation’s license is configured with a grace period of 30 days plus 2 “rearms” ( slmgr.vbs /rearm) for a total of 90 days to activate. The DNS query response includes the KMS server hostname and port number (1688). The KMS client discovers the KMS server by performing a DNS query for the KMS SRV record in DNS.ĭNS: Standard query SRV _vlmcs._ĭNS: standard query response SRV (addr 10.10.10.11) KMS supported clients include Windows Server 2008, Windows Server 2008 R2, Windows Vista, & Windows 7. Every KMS supported Windows version automatically communicates with the KMS server to activate Windows and manage the activation key (configuring the Windows OS with a KMS key forces it to find a KMS Host and get activation from it).

KMS shifts the activation requirement to a single machine which is activated with a special KMS Host (server) key. Starting with Windows Server 2008 & Windows Vista, Microsoft switched to an online activation system where every Windows OS requires activation.

The Microsoft Key Management Server (KMS) is part of the Microsoft Volume Activation 2.0 solution managing Windows OS activation keys and performs activation for supported clients automatically.

Windows server 2008 r2 license key