I have recently taken ownership of DNS in our environment. All that I know about DNS is only what I have researched on Google. That being said here is my current predicament:

We have 5 MS DNS servers in our environment. The zone in question, abc.com lets say, is setup as primary/secondary on Windows 2008.

In trying to figure out why people think the primary is "dieing" I have noticed that updates in the primary are not getting replicated to the secondaries.

All 5 servers are listed in the Name Servers tab. "Allow zone transfers" is checked with the "Only to servers listed on the Name Servers" tab option checked.

Based on what I have read I think the problem is that the SOA Serial numbers don't match between the primary server and the secondary servers:

Server 1 - primary - 992473 Server 2 - secondary - 992475 Server 3 - secondary - 992544 Server 4 - secondary - 992542 Server 5 - secondary - 992549

Am I correct in this assumption? If so can I simply manually change the SOA serial number on the primary zone to something like 2476. If I do this then all the secondary servers should automatically refresh from the primary right?

  • If you want all slaves to update you would have to choose a new serial that is higher than the highest of any of the slaves. 992550 would seem appropriate rather than your suggestion 992476 (that would only get "Server 2" to update). Sep 16, 2014 at 18:18

1 Answer 1


Indeed, if your master zone has a greater serial than all of your slaves, your slaves should synchronize to it. But the real issue here is why in the first place your slaves have a higher serial than the master's ? You should ensure that you do not have a situation of split brain DNS and that no one was able to modify the slaves in any way.

  • Our current primary replaced our previous primary dns server that apparently "died". I'm assuming that that process was kind of botched hence why our current primary is considered as "dieing". I have checked and all the other servers are set to secondary. What do you mean by "split brain DNS"? Sep 16, 2014 at 17:24
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    Split-brain DNS means that the secondaries have a different idea about the contents of your domain than the primary. This should get cleaned up automatically when the serial is used properly. You should increase the primary serial to such an extent that it gets higher than any of the existing secondaries. Sep 16, 2014 at 17:39

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