During regular check of my Hyper-V hosts (Windows servers 2008 (R2)) I have seen that some of them have time out of sync even if all of them have configured external NTP source (I am using pool.ntp.org – in my case si.pool.ntp.org (Slovenian pool))…
But by default Windows is making NTP query and correction every 7 days (604800 seconds :))…
Well as NTP query is from network prospective small / light I have decided to make this check and sync once per hour… (3600 seconds)…
Well where do we set up this?
The key that you need to change is located in:
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServices
W32TimeTimeProvidersNtpClientSpecialPollInterval
Change from 604800 to 3600 (1 hour for example)… And restart Windows Time service
You can check snapshots on:
https://skydrive.live.com/?cid=38C674F31C0CB95C&id=38C674F31C0CB95C%212390#cid=38C674F31C0CB95C&id=38C674F31C0CB95C%212391
Luka Manojlovic 
Good article, thanks for the info. Much appreciated. (The tim eon my server has been wandering for ages!)
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Instead of setting an interval of 3600 seconds (1 hour exactly), it might be better to set an interval that’s a prime number, like 3607 seconds. If you are querying the server every hour, and others are doing the same, then every so often the server will experience a high number of queries. But if your query interval is a prime number, then it will almost never overlap with the people sending queries every 3600 seconds (it will only overlap once every 3607 queries), so the load on the server will be more “smooth” instead of having bursts of high load.
This is a good general rule, in fact. If you’re setting up *any* repeating task, intervals that are prime numbers are usually better than intervals that are multiples of an hour, or a day, or a week. Or if you must have intervals that are whole days (for example, the backups must be run every night), then pick an “unusual” time like 03:19 instead of 03:00. Again, you’ll be less likely to overlap with other “run this every day” tasks, and cause more “smooth” load on the server(s).
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