During data collection phase of the IT Health Scanner, you may receive an error: “A list of servers could not be collected from Active Directory Domain Services (AD DS). Ensure that your network is functioning correctly and that this computer can access AD DS.” Cause: if you’ve a server object in AD with a blank (null) DNS hostname. Resolution: you need to locate server with blank (null) DNS hostname value, and remove the object if it is stale, or add DNSHostname Attribute with its correct value. 1. Launch elevated command prompt. 2. Run dsquery command: dsquery * domainroot -filter "(&(&(sAMAccountType=805306369)(objectCategory=computer)(objectClass=computer)(operatingSystem=*Server*)))" -attr cn DNSHostname
The output is a 2 column table displaying the cn attribute of the server and it’s DNSHostname. In this case TestMachine has a blank (null) DNSHostname Attribute.
More info: Method 2nd on EBS blog.