Answer: Layer 2, Layer 3

ExpressRoute can operate at either Layer 2 or Layer 3 of the OSI model, depending on the configuration and connectivity provider. For a Layer 2 connection, the connectivity provider supplies a direct link between the on-premises network and Azure. For a Layer 3 connection, the provider manages and configures routing on behalf of the customer. Therefore, both Layer 2 and Layer 3 are correct answers.

Author: LeetQuiz Editorial Team