This is a great reference for configuring or troubleshooting VA technical issues. 100% of the issues I had heard so far have been related to network access or name resolution. In most cases it was name resolution. The SRV record must be in the default DNS zone for the client.
The Technical Attributes document provides in detail the WMI and registry attributes where information is defined. Some of these values are configurable. For example, you can set the interval that a new KMS client that has not been activated uses to determine how frequently it should attempt to contact the server. You can provide the same interval for clients that have been activated.
Clients which have not been activated:
VLActivationInterval (default 120 or 2 hours)
The activation frequency, in minutes, of how often the current machine should contact the key management service machine before the client is licensed."
Clients that have been activated:
VLRenewalInterval (default 10090 or 7 days)
The renewal frequency, in minutes, of how often the current machine should contact the key management service machine after the client is licensed.
Both values have an acceptable range of 15 (minutes) to 43,200, or 30 days. You cannot configure the period of time used as a grace period for activated clients. An activated client has 180 days to reach the server again before it begins prompting the user to either provide a network connection where the KMS server may be contacted or enter an MAK. However, you can query this information using WMI.
This can be scripted quite easily using PowerShell. See below, simply query the SoftwareLicensingProduct class in WMI, filtering for LicenseStatus = 1 and then return Description to see what type of key is being used and GracePeriodRemaining to show how many days until the client gets in to trouble.
PS C:\>get-wmiobject softwarelicensingproduct -filter "LicenseStatus='1'" | format-table -property Description,GracePeriodRemaining
Windows Operating System - Vista, VOLUME_KMSCLIENT channel 257780
So in the above table, it appears my machine is a KMS client and has a little better than 179 days to contact the server again.