Microsoft’s Pass-Through Authentication (PTA) provides a simple, secure, and scalable method for an organization to implement and manage authentication for its users. As an important concept for the SC-300 Microsoft Identity and Access Administrator exam, it’s crucial to understand how PTA operates and how to manage its implementation effectively.
Understanding Pass-Through Authentication
PTA provides a means for users to sign in to both on-premises and cloud-based applications using the same credentials. It allows user passwords to be verified directly against the on-premises Active Directory without storing the password hashes in Azure Active Directory (Azure AD).
This authentication system operates when the Azure AD receives a password for validation, it encrypts the password with public key and places it on Azure service bus. An on-premises agent retrieves the password, decrypts it, and validates it against the on-premises Active Directory. Once the validation is complete, a response is sent back to Azure AD.
Implementing Pass-Through Authentication
To implement PTA, there are a few essential steps an administrator should follow:
- Prerequisites verification: Before deploying PTA, verify that you meet all the prerequisites. These include having an on-premises server to install the agent and that Port 80 is available for outbound connections.
- Agent Installation: Install the PTA Agent on the on-premises server. This can be done by downloading the Authentication Agent from Azure portal and following the installation prompts.
- Change the authentication method: After installing the agent, change the authentication method in Azure AD to PTA. This is done in the Azure AD Connect wizard.
- Test the configuration: Once everything is set, test the configuration by performing a sign-in activity with a few users.
| Comparison | Pass-Through Authentication | Azure AD Password Hash Sync |
|---|---|---|
| User sign-in method | Same as on-premises | Same as cloud |
| Extra server needed? | Yes | No |
| Password storage | On-premises | In Azure AD |
| Session control | Supported | Not supported |
Managing Pass-Through Authentication
PTA requires minimal management after its implementation. However, it’s recommended that you monitor the PTA service’s status and health to ensure it’s working as expected.
You also need to manage the PTA agents. You should install more than one agent, up to a maximum of 40, to set up high availability. In case one fails, the others can continue to authenticate the sign-in requests.
Moreover, periodic updates for the agents are released by Microsoft. Always ensure these updates are installed promptly to maintain the security and performance of the PTA.
In conclusion, understanding how to implement and manage Pass-Through Authentication is crucial for any administrator preparing to sit for the SC-300 Microsoft Identity and Access Administrator exam. The ability to navigate PTA’s challenges is an important skill in managing the hybrid identity in a Microsoft environment.
Practice Test
True or False: Pass-through Authentication (PTA) provides a simple password validation for Azure Active Directory (AD) authentication services.
- True
- False
Answer: True.
Explanation: PTA’s primary function is to validate users’ passwords directly against the on-premises Active Directory.
Which Azure service is primarily used to implement and manage Pass-Through Authentication (PTA)?
- a. Azure Active Directory
- b. Azure App Service
- c. Azure Logic Apps
- d. Azure DevOps
Answer: a. Azure Active Directory
Explanation: PTA is a service primarily used in Azure AD to validate users’ credentials against an on-premises environment.
True or False: It is possible to use both Pass-Through Authentication and AD Federation Services at the same time to authenticate the same user.
- True
- False
Answer: False.
Explanation: It’s not possible to use both PTA and AD Federation Services concurrently for the same user since only one authentication method can be used.
How many Authentication Agents should you ideally install for high availability of Pass-through Authentication?
- a. One
- b. Two
- c. Three
- d. None
Answer: b. Two
Explanation: It’s recommended to install at least two Authentication Agents to ensure high availability in case one agent goes down.
True or False: Every application that works with Azure AD Connect using password hash synchronization also works with Pass-through Authentication.
- True
- False
Answer: True.
Explanation: PTA supports the same set of capabilities as Azure AD Connect with password hash synchronization.
True or False: Pass-through Authentication supports user sign-ins into Microsoft
- True
- False
Answer: True.
Explanation: PTA enables users to sign in to both on-premises and cloud-based applications using the same credentials.
Which of the following is a benefit of Pass-Through Authentication (PTA)?
- a. Users need to remember multiple passwords.
- b. It does not require any on-premises components.
- c. It helps to validate users’ passwords directly against the on-premises Active Directory.
- d. It does not support seamless single sign-on.
Answer: c. It helps to validate users’ passwords directly against the on-premises Active Directory.
Explanation: The primary benefit of PTA is that it validates your users’ passwords against your on-premises Active Directory.
True or False: Pass-through Authentication requires a significant amount of on-premises resources.
- True
- False
Answer: False
Explanation: Compared to AD FS, PTA has a lighter resource footprint on-premises, as it just needs an on-premises AD agent, not a full on-premises server.
What should be enabled at user-end to support seamless single sign-on along with PTA?
- a. JavaScript
- b. ActiveX
- c. Cookies
- d. Flash
Answer: c. Cookies
Explanation: Cookies need to be enabled as PTA uses them to provide a seamless single sign-on experience for users.
True or False: Pass-through Authentication does not support smart card-based authentication.
- True
- False
Answer: True.
Explanation: As of now, PTA does not support smart card-based authentication or third-party smartcard providers.
True or False: If Pass-through Authentication Agents aren’t reachable or goes down, new sign-in requests may fail.
- True
- False
Answer: True.
Explanation: If all PTA Agents are unreachable or go down, new sign-in requests will fail, which is why a high availability setup with two or more agents is recommended.
What does the Pass-Through Authentication Agent software do?
- a. It syncs password hashes.
- b. It validates user sign-ins.
- c. It synchronizes AD objects.
- d. It creates new user accounts.
Answer: b. It validates user sign-ins.
Explanation: The purpose of the PTA Agent software is to validate user sign-ins by using a secure channel to connect directly to an existing instance of AD.
True or False: The PTA Agent can be installed on a Domain Controller.
- True
- False
Answer: True.
Explanation: Though it’s not a recommended practice due to potential performance issues, the PTA Agent can be installed on a Domain Controller.
What happens if a password is changed in the on-premises Active Directory while using Pass-through Authentication?
- a. The change won’t sync to Azure AD.
- b. The change will sync immediately to Azure AD.
- c. The change will sync after a delay to Azure AD.
- d. The user account will be locked out in Azure AD.
Answer: b. The change will sync immediately to Azure AD.
Explanation: Pass-through Authentication allows immediate password changes in Azure AD as soon as they happen in the on-premises Active Directory.
True or False: The Pass-through Authentication Agent needs to be installed on each and every on-premises computer for the users to be able to sign in.
- True
- False
Answer: False.
Explanation: The PTA Agent needs to be installed on the on-premises AD environment and not on each and every on-premises computer.
Interview Questions
What is Pass-Through Authentication (PTA)?
Pass-Through Authentication (PTA) is a method of authentication in which the validation of users’ credentials happens directly through the on-premises Active Directory. It allows the users to use the same password on-premises and in the cloud, without requiring the password hash synchronization process.
Does implementing PTA require you to open any inbound ports in your network firewall?
No, implementing PTA requires no inbound ports to be open in your network firewall. It uses secure outbound communications over HTTPS.
How does PTA handle high availability?
PTA supports high availability through installing multiple Auth Agents. These Auth Agents process sign-in requests sent to your tenants.
How is PTA different from password hash sync (PHS)?
Unlike PHS, where a hash of the user’s password hash is synchronized to Azure AD, in PTA the authentication happens in real-time against on-premises Active Directory without storing your password hash in Azure AD.
Can PTA be used together with password hash synchronization?
Yes, PTA can be used in conjunction with password hash synchronization to provide a fallback for authentication if your on-premise infrastructure is unavailable.
What is the minimum amount of Pass-through Authentication Agents required for high availability?
The minimum recommended amount for high availability is two Agents.
Is it necessary to have a seamless Single Sign-On (SSO) enabled to use PTA?
No, seamless Single Sign-On (SSO) is a complementary function but it’s not necessary. It allows users to sign in to Azure AD-based services with their organizational accounts without needing to type their passwords again.
How secure is PTA?
PTA is highly secure. It doesn’t store passwords in the cloud, and it only uses secure outbound communications, mitigating the need for inbound firewall rules.
Does PTA support smart card-based authentication?
No, PTA does not support smart card-based authentication.
Is there a way to check the status of the PTA agent?
Yes, you can check the PTA agent status at Azure AD Connect Health, to determine if the agent is working correctly.
Are there any special administrative roles needed to manage PTA?
Yes, the global administrator role is required to enable and configure PTA in Azure.
Can we use PTA if our organization is using federation with AD FS?
Yes, an organization can switch from federation with AD FS to PTA using staged rollout.
What happens if the PTA agent fails?
If one agent fails, other agents, if installed, continue to handle user authentication requests. However, if all agents are down, users can’t sign in until at least one agent is back up.
Can PTA be implemented without Azure AD Connect?
No, PTA requires Azure AD Connect to operate properly.
Does PTA support Authenticator app OTP sign-in?
Yes, PTA supports the Authenticator app OTP method for passwordless sign-in.
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