You want to implement GSLB.
Which of the following are you most likely to deploy?

A. a spine switch
B. a Cisco Nexus 1000v virtual switch
C. a leaf switch

D. a GSS device

E. an APIC server

Explanation:

Most likely, you will deploy a Cisco Global Site Selector (GSS) device if you want to implement global server load balancing (GSLB). A Cisco GSLB solution is designed to optimize Domain Name System (DNS) infrastructure, thereby ensuring business continuity in the event of disaster. When DNS services are migrated to GSS, disaster recovery is enhanced by the global load balancing of server load balancers (SLBs) across data centers in disparate geographic locations.
You will not deploy a spine switch or a leaf switch to implement GSLB. Spine switches are the Cisco FabricPath component that form the backbone of Cisco FabricPath’s switching fabric. Typically, leaf switches are connected to every spine switch along the backbone so that provides access layer connectivity. End hosts and classic Ethernet (CE) networks are typically directly connected to leaf switches by using edge ports. Leaf switches connect to spine switches by using core ports.
You will not deploy an Application Policy Infrastructure Controller (APIC) server to implement GSLB. The Cisco APIC is a means of managing the Cisco Application Centric Infrastructure (ACI). A Cisco ACI architecture requires both the APIC and the spine switches and leaf switches of FabricPath to complete the architecture. The APIC communicates with the spine and leaf nodes and provides policy distribution as well as centralized management.
You will not deploy a Cisco Nexus 1000v virtual switch to implement GSLB. The Cisco Nexus 1000v is a virtual switch that is designed to provide a switching environment for virtual machines (VMs) and cloud networks. Typically, a Cisco Nexus 1000v is embedded in the kernel of VMware vSphere ESX.

Reference:

Cisco: Introducing the Global Site Selector: GSLB Using the GSS