What Time Is It

What Time Is It

This month, let's take some time to discuss time. I will concentrate on two time facets. The first will be how the Internet keeps track of email time even as email travels across time zones. The second will be how you can synchronize your computer to one of the Internet's authoritative timeservers.

Internet time is based on Greenwich Mean Time (GMT). This is the London time zone. All other time zones are either viewed as GMT + or GMT -. For example, Berlin is GMT + 1, Athens is GMT +2 and Moscow is GMT +3. These cities officially begin each day and year before London. On the flip side, Chicago is GMT -6, Denver is GMT -7 and Sacramento is GMT -8. These cities officially begin each day and year after London.

Internet mail servers synchronize to GMT. This helps them keep track of time as email travels across time zones. Suppose I send an Internet message from Sacramento at 2:00 to a friend in Chicago. He receives it one minute later, at 4:01 Chicago time and replies at exactly 4:30 Chicago time. I receive it one minute later at 2:31 Sacramento time. How does this work?

Most Internet messages are recorded in GMT. Your email client (e.g. Outlook, Eudora, Yahoo mail) merely adjust the time when presenting the time sent or received. The message I discussed above was actually sent at 10:00 GMT and received at 10:01. My friend replied at 10:30 and I received the message at 10:31 GMT. Our email clients mask the time and adjust it for the local time zone.

Now that we understand time zones and how our email clients mask the actual time, let's make sure your computer's time is accurate. Several Internet authoritative timeservers precisely track time and permit other computers to synchronize with them. Some of these are at time.microsoft.com, ntp2.usno.navy.mil and tock.usno.navy.mil.

For these instructions, I'm assuming that you're running Windows XP or 2000. If you're running Windows XP Home, simply double-click the time (lower right-hand corner), and tell Windows to synchronize with the default timeserver at time.microsoft.com. Click the OK button when done.

If you're running Windows 2000 or Windows XP Professional, start by clicking the START button. Choose RUN, type command and press (Enter). Enter the command: net time /setsntp: ntp2.usno.navy.mil and press (Enter). Next type net time /set and press (Enter). Type exit and press (Enter) to exit the command prompt.

Also make sure your time zone is accurate. Double-click the time and choose the TIME ZONE tab. Verify that your time zone is set to "(GMT-8:00) Pacific Time…" If it isn't set correctly, change the time zone. Press (Enter) when done.