Daylight Savings Time Frequently Asked Questions

Q1. Can the DST change be made by simply updating the system clock?

A1. This is not recommended. If the former DST rules still are defined in your system, a simple change of the clock will not change the DST rules that are used in time and date calculations.

Q2. What caused the need to change the Daylight Saving Time rules for our hardware and software products?

A2. In the U.S., the Energy Policy Act of 2005 changed the rules for Daylight Saving Time (DST). These new rules will go into effect in March 2007. Canada and Bermuda made similar changes to their DST rules to be consistent with the U.S. time changes. DST rules affect date and time processing functions in computers and applications. If not set properly, the time could be incorrect by one hour for four weeks each year. Since DST rules have been relatively stable in these countries for many years, people have come to rely upon automated adjustments in time in connection with their information technology.

Q3. What are the new dates for the Daylight Saving Time schedule in the U.S., Canada and Bermuda?

A3. Starting in 2007, Daylight Saving Time for the U.S., Canada and Bermuda will be extended by four weeks, starting three weeks earlier on the second Sunday in March and ending one week later on the first Sunday in November. In 2007, DST will start on Sunday, 11 March and will end on Sunday, 4 November.

Q4. Who is affected?

A4. Daylight Saving Time rules changes could affect any computers, applications and electronic devices that have built-in DST rules for date and time processing. This is not a vendor specific issue.

Q5. What is affected by the DST changes?

A5. Computers and applications in the U.S., Canada and Bermuda with date and time processing functions will be affected. Computers and applications in other countries that are not implementing the DST changes also could be impacted if they support users, transactions or applications in the countries that are changing DST. Computers and applications that interact with the U.S., Canada or Bermuda on a time sensitive basis should be updated.

Q6. I understand that in various parts of the world DST rules have changed many times in the past. Why is this change different?

A6. This has been a concern in the past. For example, Australian clients had to take action when their DST rules were changed to accommodate the Commonwealth Games in early 2006. This U.S. Energy Act change is likely to impact a high proportion of users because of the economic size of the countries involved in changing DST rules and the number of systems that may have time-sensitive interactions with these countries. In addition, as time goes on, more systems are supporting users in multiple countries. These factors combine to make this a good time to understand this issue, assess the impact on your computers and applications (if any), and plan appropriate action.

Q7. My system time is kept up to date by an external time service. Do I need to do anything?

A7. External time services normally only update your system clock and do not change DST rules kept in other parts of your computer or applications. The DST rules need to be changed in all of the places where the rules may be currently kept.


About Brent Whitfield

Brent Whitfield is CEO of DCG Technical Solutions, Inc., which provides IT Support in the Los Angeles area since 1993. DCG exists to help our clients choose, implement, and manage IT and cloud solutions that are cost effective and reliable. DCG's pro-active approach to IT is ideally suited for companies who depend on reliable IT infrastructure, but don't want to spend a lot of money to keep it that way. DCG was recognized among the Top 10 Fastest Growing MSPs in North America by MSP Mentor. Brent has been featured in Fast Company, CNBC, Network Computing, Reuters, and Yahoo Business.


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