Microsoft 365 tenant lookup
Enter a domain to find its Microsoft 365 / Entra tenant ID, region, cloud and sign-in type. Only public data is read: no login, nothing sent to the tenant.
What the lookup shows
Tenant ID and name
From Microsoft's public OpenID discovery document for the domain, and the organisation name its sign-in page shows.
Region and cloud
Where the directory is homed (for example Europe or North America) and which Microsoft cloud it belongs to: global, US Government (GCC High / DoD) or China (21Vianet).
Sign-in type
Managed or federated, from the same realm lookup a Microsoft sign-in page does when you type an address. No account is needed and nothing is sent to the tenant.
Exchange Online DNS
Whether MX points at Exchange Online, whether the MS= verification TXT record is still published and where autodiscover points.
Questions
What is a Microsoft 365 tenant ID?
The GUID that identifies an organisation's Microsoft Entra ID (formerly Azure AD) directory. Every Microsoft 365, Azure and Dynamics subscription of that organisation lives in it. Admins need it for app registrations, PowerShell sign-ins, conditional access exclusions and support cases.
Is it a problem that anyone can look it up?
No. The tenant ID is not a secret: Microsoft publishes it in the sign-in discovery document of every verified domain, and sign-in pages use it. Security comes from authentication and Conditional Access, not from hiding the ID.
Managed or federated sign-in?
Managed means users sign in to Microsoft directly (cloud passwords, password hash sync or pass-through authentication). Federated means sign-in is handed to another identity provider, such as AD FS, Okta or Ping, shown here by its host name.
Why is a domain not found?
The domain is not verified in any Microsoft Entra tenant, or it is verified in a sovereign cloud that the public discovery endpoint does not answer for. Subdomains are only found when they are verified on their own.
Go further
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See inside the tenant, read-only
ConfigCobra checks Microsoft 365 against the CIS benchmark and shows inactive users, guests, app secrets and more.