Which Cisco NX-OS feature automates the process of upgrading software images and installing configuration files on Cisco Nexus switches that are being deployed on the network?

Configuration synchronization typically refers to maintaining consistent configurations across multiple devices, often within a high-availability setup, rather than initial automated deployment and upgrade.

Cisco's PowerOn Auto Provisioning (POAP) is an NX-OS feature designed to automate the initial configuration and software image upgrade process for new or factory-reset Cisco Nexus switches, allowing them to self-provision when powered on.

REST (Representational State Transfer) is an architectural style for APIs, not a specific feature for automating software upgrades and initial configuration.

NX-API is a programmatic interface for interacting with NX-OS devices, used for automation and integration, but it is not the specific feature that automates initial software upgrade and configuration during deployment.