Small Business Server 2008

Hi all,

We have a Small Business Server 2008 which is running into a huge issue.

Two times now we have run into a situation where all users are having DNS failures causing the internet to not work.

After some investigation we found the server had managed to change its IP from to

This has happened twice now.

Has anyone ever had this happen to them?

Its causing major down time.

Do you think it will be worth replicating the DNS on another one of our servers then pointing DHCP to that - although does this require the server being promoted to a Domain Controller?


Optima SystemsNetwork EngineerAsked:
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Patrick de GelderSupport engineerCommented:
First I would figure out what exactly is happing.
DNS should be configured with a static IP address and static ipaddress doesn't change just like that.

- It might because of  policy that gets enforced.
- Or conflict with an other process/device
- TCP/IP configuration not set properly

by the way... when did you notice this issue for the first time and what was the exact time between the first and the second time...

When was the last time system has been rebooted.

Would it be possible that there is a second DHCP server is installed on your network or an other device that provide automaticly DHCP.
David AtkinTechnical DirectorCommented:
Hi James,

Presuming you only have the once NIC enabled on the server?

Anything in the event logs?
David SairaiTechnical SpecialistCommented:
I suspect you have a DHCP server somewhere on your network. Put a static IP on this server ( Also run "arp -a" at command prompt see the contents of the local ARP cache table. You could see what "devices" where in "touch".
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David AtkinTechnical DirectorCommented:
Another thought,

Do you know if the server was ever configured via the SBS Wizards?

Run the Fix My Network Wizard from the SBS Console to check the network configuration.
SBS Console> 'Network' Tab> 'Connectivity' sub tab> 'Fix My Network wizard' on the right hand side
Optima SystemsNetwork EngineerAuthor Commented:
Thanks for your help everyone.

It turned out to be a weird issue. I think something else running DHCP may of been the culprit. However, more worryingly, something had stolen our Public IP. We managed to fix it by blocking the MAC address of the device taking the IP. We are now trying to find the culprit.



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Patrick de GelderSupport engineerCommented:
Hi James,

Its nice to get some feedback good luck with finding the culprit.

Optima SystemsNetwork EngineerAuthor Commented:
Fix was unrelated.
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