Is it true that a minimum of two co-located TAs are necessary to prevent service interruption?

Having a minimum of two co-located Trust Authorities (TAs) is indeed essential for ensuring the continuity and reliability of a Public Key Infrastructure (PKI) environment. This concept is grounded in the need for redundancy and high availability in critical security services, particularly those that issue and manage digital certificates.

When TAs are co-located, it enhances the resilience of the system against possible failures, whether they be technical malfunctions, system crashes, or natural disasters. By having at least two TAs, the PKI can seamlessly distribute the workload and provide services even if one TA becomes unavailable. This redundancy is crucial because PKI operations, such as certificate issuance and revocation, are fundamental to maintaining trust in the system. A service interruption could compromise security and hinder normal operations, potentially impacting users relying on secure communications.

While some alternatives may suggest that one TA could suffice during specific times or newer deployments, the regular operational integrity and security of a PKI framework are best supported by the redundancy provided by multiple TAs. This configuration guarantees that there is always an operational TA available to maintain critical functions and uphold the trust that PKI systems are built upon.