When you try to install the Microsoft Azure Active Directory Sync Tool, you may receive the following error message:
The computer must be joined to a domain.
This issue may occur if the computer isn't joined to an Active Directory Domain Services (AD DS) domain or if the computer doesn't register a host (A) resource record with its Domain Name System (DNS).
To resolve this issue, use one of the following methods.
Method 1: Computer isn't joined to an AD DS domain
Join the computer to an AD DS domain. To do this, follow these steps:
On the computer that you want to join to a domain, click Start, click Control Panel, and then double-click System.
Under Computer name, domain, and workgroup settings, click Change settings.
On the Computer Name tab, click Change.
Under Member of, click Domain, type the name of the domain that this computer will join, and then click OK.
Click OK, and then restart the computer.
Method 2: Computer is already joined to an AD DS domain
If the computer is already joined to an AD DS domain, make sure that the computer's DNS settings are correct and that a host (A) resource record for the computer is registered with DNS. To do this, follow these steps:
Open Network Connections.
Right-click the network connection that you want to set up, and then click Properties.
Do one of the following, as appropriate for the connection that you want to set up:
For a local area connection: On the General tab, click Internet Protocol (TCP/IP), and then click Properties.
For all other connections: On the Networking tab, click Internet Protocol (TCP/IP), and then click Properties.
If you want to obtain DNS server addresses from a Dynamic Host Configuration Protocol (DHCP) server, click Obtain DNS server address automatically.
If you want to configure DNS server addresses manually, click Use the following DNS server addresses. In the Preferred DNS server box, type the IP addresses of the preferred DNS server. In the Alternate DNS server box, type the IP addresses of the alternative DNS server.
Click OK two times, and then close Network Connections.
At a command prompt, type the following commands, and press ENTER after each command:
ipconfig /flushdns ipconfig /registerdns
If the issue isn't resolved, restart the computer that has Directory Sync Tool installed.
If the issue still isn't resolved, make sure that the computer that has the Directory Sync Tool is installed can communicate with the computer that's running AD DS.
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