Which IEEE standard provides the capability to permit or deny network connectivity based on the user or device identity?

802.1D is the original standard for Spanning Tree Protocol (STP), which prevents loops in bridged networks.

802.1w is Rapid Spanning Tree Protocol (RSTP), an enhancement to STP for faster convergence.

802.1Q is the standard for VLAN tagging, which segments networks into virtual LANs.

IEEE 802.1X is a port-based network access control standard that provides an authentication mechanism for devices connecting to a LAN or WLAN, allowing network administrators to restrict unauthorized devices from connecting to a network. It uses an authenticator (switch/AP), supplicant (client), and authentication server (RADIUS) to verify identity.