The correct answer is C. The data plane is based on VXLAN. In Cisco SD-Access, the fabric uses: * LISP for the control plane * VXLAN for the data plane * Cisco TrustSec / SGT-based policy for the policy plane Cisco documentation explicitly states that SD-Access uses a LISP-based control plane and a VXLAN-based data plane. VXLAN is the encapsulation technology used to transport user traffic across the SD-Access fabric overlay. This is why the data plane in Cisco SD-Access is based on VXLAN. * A. Dynamic routing is used to discover and provision border and edge switches. Dynamic routing may exist in the underlay, but it is not what "discovers and provisions" border and edge nodes in SD-Access. Provisioning is handled through Cisco DNA Center / Cisco Catalyst Center, not by dynamic routing itself. * B. The control plane is based on VXLAN. This is incorrect because the control plane in SD-Access is based on LISP, not VXLAN. * D. GRE is used as the policy plane. This is incorrect because the policy plane in SD-Access is based on TrustSec/SGT-based policy, not GRE. ENCOR exam point: Memorize this SD-Access mapping: * Control plane = LISP * Data plane = VXLAN * Policy plane = Cisco TrustSec / SGT