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I have a Server with a statically set IP address of 10.200.0.30

It has a Dynamic DNS entry matching its computer name to its IP

Every hour on the hour it changes its DNS entry to a random IP address in my 10.54.0.0 subnet.

What in the world is going on here? The IP is statically set on the NIC. DNS just feels like changing its entry ever hour.

When I checked the timestamp I also noticed that just about all my DNS entries are updated every hour.

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My DHCP lease time is set to 6 hours for both the 10.200 zone and 10.54 zone.

The 10.200 zone has all IP addresses excluded from the range. Reservations only.

Any help would be greatly appreciated. Thanks!

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I have added additional information to my question. –  Ruisu Oct 14 '11 at 20:46
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2 Answers

According to your other question you have a DHCP server running. So someone has set the lease time to one hour.

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Do you really think every client would recieve the lease at exactly the same time? See the 'on the hour' point, and that all of clients are exactly at the same time to the second. It seems extremely unlikely to me that this is 'normal' renewals for a 1 hour lease. –  Zoredache Oct 14 '11 at 19:23
    
@Zoredache No, not really. But who told you that the timestamp column is the date where the lease was given out? –  mailq Oct 14 '11 at 19:25
    
Since your answer is about the lease time, I am assuming standard Windows Dynamic DNS behavior on the client & DHCP server. It tries to update, when a DHCP request has been received. It seems very unlikely that every client machine would in sync. –  Zoredache Oct 14 '11 at 19:42
    
So it is not every machine updating on the hour. Approx 20 or so. Then, another group of 20 the next hour and so on. It just DNS entry that is having the issue of changing the IP address for no reason. –  Ruisu Oct 14 '11 at 20:43
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DNS A records register\refresh updates are stamped ROUNDED DOWN to the nearest hour - you're seeing normal behaviour

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