Within a second is not very close. Less than.5 second is good, 50 ms is about the best any non-realtime OS can do.
If you have a network (not just a couple of machines, there are multiple issues involved in keeping the entire network synchronized. Some do it by regular broadcast (very problematic), some by regular schedule (okay, but not optimal) and some by target seeking.
Check out our product - http://www.greyware.com/domaintime for a program that takes all of the above into account.
Actually, the battery-backed hardward clock on a PC is used only to keep time while the machine is off, and is usually accessed (depending on the operating system - some do it more often) only when the machine is booting. After the OS is running, time is kept by the OS itself using software timer. Depending on how busy the machine is, the software clock can speed up or slow down, and on some systems, clocks can drift by entire hours or days in a relatively short period.
Why go 3rd-party? Because, NET TIME (and Windows Time) is fraught with problems, particularly in a larger network/mixed environment. More detailed info about this at our site http://www.greyware.com/software/domaintime/produc t/w32time.asp
Yes, I work for them, but I'd use this even if I didn't.
Anyone interested in the various problems with w32time (the Win2k/XP time program) and NET TIME (the MS command-line time sync) should read http://www.greyware.com/software/domaintime/produc t/w32time.asp
Disclaimer: Yes, I work for the above company that sells time sync products.
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Within a second is not very close. Less than .5 second is good, 50 ms is about the best any non-realtime OS can do.
If you have a network (not just a couple of machines, there are multiple issues involved in keeping the entire network synchronized. Some do it by regular broadcast (very problematic), some by regular schedule (okay, but not optimal) and some by target seeking.
Check out our product - http://www.greyware.com/domaintime for a program that takes all of the above into account.
Actually, the battery-backed hardward clock on a PC is used only to keep time while the machine is off, and is usually accessed (depending on the operating system - some do it more often) only when the machine is booting. After the OS is running, time is kept by the OS itself using software timer. Depending on how busy the machine is, the software clock can speed up or slow down, and on some systems, clocks can drift by entire hours or days in a relatively short period.
Why go 3rd-party? Because, NET TIME (and Windows Time) is fraught with problems, particularly in a larger network/mixed environment. More detailed info about this at our site http://www.greyware.com/software/domaintime/produc t/w32time.asp
Yes, I work for them, but I'd use this even if I didn't.
Anyone interested in the various problems with w32time (the Win2k/XP time program) and NET TIME (the MS command-line time sync) should read http://www.greyware.com/software/domaintime/produc t/w32time.asp
Disclaimer: Yes, I work for the above company that sells time sync products.