
When it comes to hybrid AD setup, we have to work with whole different types of issues than on-premises AD environments. Azure AD is a managed service by Microsoft, so there is nothing we can do to manage its health. Therefore, most of the hybrid AD issues are related to connectivity, Directory sync, or authentication methods (password hash, pass-through authentication, federated). The main component which connects the on-premises Active Directory environment with Azure AD is Azure AD Connect. So most of the issues in the hybrid environment can also be related to Azure AD Connect. See the following articles for Azure AD Pass-Through Authentication with on-Premise AD, reasons to deploy AAD, and how to set up an Azure AD Tenant. Also, see the following article on how to add a custom domain in the Azure Active directory.
Azure AD connect has built in tool for troubleshooting to cover most of these scenarios. Based on the symptoms, the tool will run pre-built tests and provide insights which help to find the root cause.
Built-in Azure Active Directory Connect tool
Launch the AD Connect tool as shown below
– Select Troubleshooting and on the right hand pane of the Window
– Select Launch

This will open up a windows PowerShell session displaying various options to select from depending on your issue.

On the prompt: Please make a selection, enter your desired number e.g “5” and hit enter.
– Follow up from here as your issue can be very specific.
I hope you found this blog post on the built-in Azure Active Directory Connect tool helpful. Please let me know in the comment session if you have any questions.