A secure communication link needs to be configured between data centers via the internet.

IPSec (Internet Protocol Security) is the best choice for secure communication over the internet, as it provides encryption, authentication, and data integrity. It is widely used in VPNs and site-to-site secure tunnels.

Breakdown of Options:

A. DCI (Data Center Interconnect) – A general term for linking data centers, but it doesn’t specify a secure tunneling protocol.

B. GRE (Generic Routing Encapsulation) – Encapsulates traffic but lacks encryption, making it less secure than IPSec.

C. VXLAN (Virtual Extensible LAN) – Used for Layer 2 network overlays, not for securing communication over the internet.

D. IPSec – ✅ Correct answer. Provides encryption, authentication, and integrity for data over the internet.