The importance of time

All devices have an internal clock (routers, switches, your PC, etc).

In Cisco IOS, you can view the time with the show clock command.

R1# show clock
*00:16:00.87 UTC Sat Dec 26 2020

The default time zone is UTC (Coordinated Universal Time).

If you use the show clock detail command, you can see the time source.

R1# show clock detail
*00:19:49.411 UTC Sat Dec 2 2020
Time source is hardware calendar

* = time is not considered authoritative

Time source is hardware calendar - The hardware calendar is the default time source.

The internal hardware clock of a device will drift over time, so it is not the ideal time source.

From a CCNA perspective, the most important reason to have accurate time on a device is to have accurate logs for troubleshooting.

Syslog, the protocol used to keep device logs, will be covered later.

Logs