The correct answer is B. Kerberos token, because Kerberos authentication relies heavily on precise system time synchronization between clients, servers, and the Key Distribution Center (KDC). Kerberos uses time-stamped tickets to prevent replay attacks, and even small time discrepancies can cause authentication failures.
According to the Quentin Docter – CompTIA A+ Complete Study Guide, Kerberos requires clocks on all participating systems to be synchronized within a narrow tolerance (typically five minutes). If system time is inaccurate, Kerberos will reject authentication requests, resulting in login failures and access denial.
The Travis Everett & Andrew Hutz – CompTIA A+ All-in-One Exam Guide explains that Kerberos tokens include timestamps to ensure tickets are valid only for a short time window. This security design protects against attackers reusing captured authentication data.
The Mike Meyers / Mark Soper Lab Manual reinforces that time synchronization issues are a common cause of Kerberos-related login problems in domain environments. Services like TACACS+, RADIUS, and WPA do not depend on strict system time synchronization in the same way Kerberos does.
Because Kerberos authentication cannot function correctly without accurate system time, B is the correct answer.
