Setting the Time Zone


You want to change the time zone on the router.


To configure the router's local time zone, use the following configuration command:

Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#clock timezone EST 5

The clock timezone configuration command accepts any freeform zone name (EST, PST, Eastern, etc.), followed by an offset from the UTC (24 to 24 hours) and an optional offset from UTC in minutes for areas that require it.


By default, the router uses UTC, also called Coordinated Universal Time. UTC, formerly known as Greenwich Mean Time (GMT), has become the worldwide standard for time and date. The principles for calculating local time zones from UTC are the same as for GMT. The only difference is that UTC is based on precise atomic clocks, shortwave radio signals, and satellites to ensure accuracy, which need not actually be located in Greenwich, England.

It is useful to set the router's internal system clock to display the time in the local time zone. North American clocks set to UTC, for example, display the time between five and eight hours ahead of the local time. This means that somebody reading the clock has to do some mental arithmetic to translate to local time, which is sometimes awkward and makes correlating the times of network problems more difficult than it needs to be.

You can view the current time zone information with the show clock detail command:

Router>show clock detail
14:27:31.415 EST Sun Jan 29 2006
Time source is NTP

Many organizations choose to configure all of their routers to the same time zone to ease problem correlation, regardless of router location. The network administrators will configure all of their routers to the same time zone, even if they are physically located in a different part of the world. We recommend doing this because it simplifies troubleshooting by eliminating the need to do a lot of mental arithmetic that can unnecessarily slow down an already difficult and stressful situation.

Table 14-1 shows the configuration for several of the most commonly used time zones in North America. A detailed list of worldwide time zones is located in Appendix B.

Table 14-1. North American time zones

Time zone Abbr. Offset from UTC Configuration command
Hawaiian Standard Time HST UTC -10
clock timezone HST
Alaska Standard Time AKST UTC -9
clock timezone AKST
Pacific Standard Time PST UTC -8
clock timezone PST
Mountain Standard Time MST UTC -7
clock timezone MST
Central Standard Time CST UTC -6
clock timezone CST
Eastern Standard Time EST UTC -5
clock timezone EST
Atlantic Standard Time AST UTC -4
clock timezone AST
Newfoundland Standard Time NST UTC -3.5
clock timezone NST
3 30


See Also

Recipe 14.4; Recipe 14.5; Appendix B

Router Configuration and File Management

Router Management

User Access and Privilege Levels


IP Routing





Frame Relay

Handling Queuing and Congestion

Tunnels and VPNs

Dial Backup

NTP and Time


Router Interfaces and Media

Simple Network Management Protocol





First Hop Redundancy Protocols

IP Multicast

IP Mobility




Appendix 1. External Software Packages

Appendix 2. IP Precedence, TOS, and DSCP Classifications


Cisco IOS Cookbook
Cisco IOS Cookbook (Cookbooks (OReilly))
ISBN: 0596527225
EAN: 2147483647
Year: 2004
Pages: 505 © 2008-2020.
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