Marty: You’re not gonna believe this. We have to go back to 1955
Doc: I don’t believe it!
Marty: That’s right, Doc. November 12th, 1955.
Doc: Unbelievable that Old Biff could’ve chosen that particular date. It could mean that that point in time inherently contains some sort of cosmic significance, almost as if it were the temporal junction point of the entire space-time continuum. On the other hand, it could just be an amazing coincidence.
– Back to the Future Part II
– Robert Zemeckis and Bob Gale
To view the system time on a router, use the show clock command:
DocBrown>en Password: DocBrown#show clock *04:53:21.590 UTC Wed Mar 1 1993
The asterisk in front of the time indicates that the time value is not authoritative. A time of March 1 1993 is the default time value when you turn on a router that has neither NTP configured, nor a manually-configured time.
A show clock detail confirms that no time source has been configured:
DocBrown>en Password: DocBrown#show clock detail *04:55:06.999 UTC Wed Mar 1 1993 No time source
To set up the system time manually, use clock timezone (to set the timezone) and the clock set (to set the time). Configure the timezone before you configure the time because any change from the default UTC timezone will also alter the system time, and you’ll have to reconfigure the time again. So, save a step and do the timezone first:
DocBrown#conf t Enter configuration commands, one per line. End with CNTL/Z. DocBrown(config)#clock timezone PST -8 DocBrown(config)#exit DocBrown#clock set 22:04:00 12 November 1955 ^ % Invalid input detected at '^' marker. DocBrown#clock set 22:04:00 12 November ? Year DocBrown#clock set 22:04:00 12 November 2015
Doc Brown cannot go back to 1965 because the acceptable range of values for year is 1993 to 2035. So, let’s send him to 2015 instead.
To verify, use the show clock command:
DocBrown#show clock 22:04:05.311 PST Thu Nov 12 2015
The asterisk in front of the time is gone now, indicating that the time value is authoritative.
Now show clock detail shows that it is a user-configured time:
DocBrown#sh clock detail 22:48:59.047 PST Thu Nov 12 2015 Time source is user configuration