Troubleshooting & Common Mistakes

Client Cannot Join the Domain

• Client VM is on a different virtual network
• Client DNS is not pointing to the domain controller
• Domain controller is powered off or unreachable

Domain joins rely entirely on DNS. The client must be able to locate a domain controller using DNS records.

On the client, verify DNS configuration:

ipconfig /all

The DNS server should be the domain controller’s private IP address — not a public resolver.

Login Fails After Domain Join

• The machine was not rebooted after joining the domain
• The user logged in with a local account
• The username format is incorrect

Always log in using the domain-qualified username:

DOMAIN\username

Logging in locally bypasses Active Directory entirely.

User Can Log In but Lacks Expected Access

• User is not a member of the correct security group
• Group membership was added after the user logged in

Group membership is evaluated at logon. Changes do not apply until the user logs out and back in.

From the client, verify the user’s security token:

whoami /groups

This output shows the groups included in the user’s access token and explains why access is granted or denied.

Computer Account Not Appearing in Active Directory

• The client joined the domain but has not rebooted
• Active Directory Users and Computers was not refreshed

By default, new computer accounts are created in the built-in Computers container.

Refresh the console or restart it if the object does not appear immediately.

A Practical Troubleshooting Order

• Verify network connectivity
• Verify DNS configuration
• Confirm authentication credentials
• Check group membership and tokens
• Reboot when appropriate

Active Directory issues are rarely caused by the directory itself. Networking and DNS are almost always the root cause.