Computing & Information Services

Public Server Services - Macintosh Division

Welcome to the UNH CIS DST Mac Techie Page.

Here's how you can check your ZoneInfo database to verify when DST goes into effect on YOUR Macintosh:

This is fairly TECHNICAL and involves using the Terminal program to 'poke around' in the 'guts' of your Mac OS. If you are not comfortable working in a command line environment, this is likely not for you!

Here are the steps to check your Mac's main ZoneInfo database. The results you get will tell you if your Mac knows about the new DST dates for 2007 and beyond.

  • Open your Terminal application from the Utilities folder inside your Applications folder.
  • At the command prompt, type this: ls -la /etc/localtime
  • You will see that 'localtime is a symbolic link pointing to your Mac's local time zone. Which is likely to be: /usr/share/zoneinfo/US/Eastern
  • Now type in this: zdump -v /etc/localtime | grep 2007
  • If your Mac is aware of the new DST settings, you should see this:

/etc/localtime Sun Mar 11 06:59:59 2007 UTC = Sun Mar 11 01:59:59 2007 EST isdst=0
/etc/localtime Sun Mar 11 07:00:00 2007 UTC = Sun Mar 11 03:00:00 2007 EDT isdst=1
/etc/localtime Sun Nov 4 05:59:59 2007 UTC = Sun Nov 4 01:59:59 2007 EDT isdst=1
/etc/localtime Sun Nov 4 06:00:00 2007 UTC = Sun Nov 4 01:00:00 2007 EST isdst=0

  • What you want to see is that March 11 and Nov 4 are being referenced.
  • If, instead, you see this:

/etc/localtime Sun Apr 1 06:59:59 2007 GMT = Sun Apr 1 01:59:59 2007 EST isdst=0
/etc/localtime Sun Apr 1 07:00:00 2007 GMT = Sun Apr 1 03:00:00 2007 EDT isdst=1
/etc/localtime Sun Oct 28 05:59:59 2007 GMT = Sun Oct 28 01:59:59 2007 EDT isdst=1
/etc/localtime Sun Oct 28 06:00:00 2007 GMT = Sun Oct 28 01:00:00 2007 EST isdst=0

  • Then your Mac will need to be updated.
  • Go to the CIS DST Update page to see which steps to take next.

For the latest information about Apple Computer, Mac OS X Server, and other Apple server products, visit:

If you have a question or encounter a problem with your Macintosh hardware or software you can: