Which description of switch discovery on a Cisco APIC is true?
A. The APIC assigns an IP address to the switch from a pool.
B. Only leaf switches are discovered automatically.
C. A switch can be registered to multiple APIC clusters.
D. A switch registers with the APIC automatically.
Correct is A
Each APIC instance in the cluster first discovers only the leaf switch to which it is directly connected. After the leaf switch is registered with the APIC, the APIC discovers all spine switches that are directly connected to the leaf switch.
As each spine switch is registered, that APIC discovers all the leaf switches that are connected to that spine
switch. This cascaded discovery allows the APIC to discover the entire fabric topology in a few simple steps.
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/2-x/GSG/b_APIC_Getting_Started_Guide_Rel_2_x/b_APIC_Getting_Started_Guide_Rel_2_x_chapter_0100.pdf
Answer is A
Only A is True
“The ACI fabric is brought up in a cascading manner, starting with the leaf nodes that are directly attached to the APIC. LLDP and control-plane IS-IS convergence occurs in parallel to this boot process. The ACI fabric uses LLDP- and DHCP-based fabric discovery to automatically discover the fabric switch nodes, assign the infrastructure VXLAN tunnel endpoint (VTEP) addresses, and install the firmware on the switches.”
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/1-x/aci-fundamentals/b_ACI-Fundamentals/b_ACI-Fundamentals_chapter_010011.html