Your organization uses Microsoft Entra ID and wants to implement a passwordless authentication strategy. Users have smartphones. Which method should you recommend as the primary authentication method?
Microsoft Authenticator app with passwordless sign-in is the correct choice because it leverages the user's smartphone as a possession factor, using a cryptographic challenge-response protocol. When the user enters their username, the Authenticator app displays a number or a number match prompt; the user's approval signs the request with a private key stored in the device's secure enclave, eliminating the password entirely. This method is phishing-resistant, supports conditional access policies, and works seamlessly on iOS and Android, making it ideal for smartphone-centric users.
Why this answer
The Microsoft Authenticator app with passwordless sign-in is the correct primary method because it leverages the user's smartphone to provide a seamless, phishing-resistant authentication experience using public/private key cryptography (FIDO2/WebAuthn). This method aligns with the organization's goal of eliminating passwords while utilizing existing smartphone hardware, and it supports a simple user experience by requiring only a biometric or PIN verification on the phone.
Exam trap
The trap here is that candidates often confuse 'passwordless' with 'MFA' and select SMS-based authentication, not realizing that SMS still relies on a shared secret (the code) and is not truly passwordless or phishing-resistant.
How to eliminate wrong answers
Option A is wrong because FIDO2 security keys are hardware tokens that require additional procurement and distribution, making them less practical as a primary method for all users who already have smartphones. Option C is wrong because SMS-based authentication is not passwordless (it still relies on a one-time code sent via text) and is vulnerable to SIM-swapping and phishing attacks, failing to meet the passwordless strategy's security goals. Option D is wrong because Windows Hello for Business is tied to Windows devices and does not leverage smartphones, so it cannot serve as the primary method for users who may not always have access to a Windows PC.