D. IPSec. IPSec provides authenticated and encrypted communication at the network layer and is the standard, most secure method for site-to-site connectivity over untrusted networks. It ensures confidentiality, integrity, and authenticity of traffic between sites. Why The Other Options Are Incorrect A. VXLAN. VXLAN is an overlay tunneling protocol used to extend Layer 2 networks over Layer 3 infrastructure. It does not provide encryption or security by default. B. IKE. IKE is a key management an

C. Warm. A warm site maintains partially active infrastructure and regularly updated data but does not run full production workloads. It allows a moderate recovery time objective and some acceptable downtime, which aligns with non-critical applications that can tolerate a short service interruption. Why The Other Options Are Incorrect A. Hot. A hot site is fully operational with real-time data replication and near-zero downtime, which is excessive and unnecessarily costly for non-critical applic

A. PKI. X.509 certificates are the standard digital certificate format used in Public Key Infrastructure to bind public keys to identities and enable authentication, encryption, and digital signatures. Why The Other Options Are Incorrect B. VLAN tagging. VLAN tagging is a Layer 2 network segmentation mechanism and has no relationship with digital certificates or identity validation. C. LDAP. LDAP is a directory service protocol that can store or reference certificates, but X.509 certificates are