Linux tracks two clocks: the system clock (software, maintained by the kernel in RAM) and the hardware clock (RTC on the motherboard, runs when the machine is off). On a running system, the kernel trusts the system clock. At boot, systemd reads the RTC to seed the system clock, then hands off to chrony (the default NTP client on RHEL) to keep it accurate over the network. timedatectl is the single CLI that shows you the current state of both clocks, the timezone, and whether NTP sync is active. Accurate time is not optional: Kerberos authentication fails if clocks drift more than 5 minutes, TLS certificates are validated against the current time, and log correlation across hosts breaks down if timestamps disagree. On the RHCSA, expect tasks like "set the timezone to America/Chicago" or "enable NTP synchronization".
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