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DNS Host Record - Static IP Changes in DNS to DHCP IP

Posted on 2006-06-08
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Last Modified: 2010-03-19
We have an interesting DNS issue on a Windows 2003 domain running AD.  We have a web server set with a static IP address.  The host address of the web server is initially set in DNS mapped to the static address. What happens is (for some reason) that host address changes in DNS from the static IP address to another IP address (an address distributed by the DHCP server).  

Now when you do a ping, for example, DNS resolves the web server name with the incorrect DHCP address.  I can still ping the original static address, but for some reason the DNS gets changed and no longer resolves to the correct IP… I can manually change the host in DNS (on the DNS server) back to the static address, but this process continuously repeats and the static map in DNS changes to the same DHCP address.  I’ve manually deleted the bogus DHCP address mapping from the DHCP server too.

Like I said the NIC is set to static, to the best of my knowledge there are no other devices on the network with that name, and I haven’t had any IP conflicts.

At this point I’m not sure what else it can be, so I’m posting here.
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Question by:CecilAdmin
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Accepted Solution

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Imtiaz Hasham earned 675 total points
ID: 16860918
Hi,

Could you kindly confirm how many network cards do you have on the Web server.

For a start, take the MAC address of the Network Interface Card and reserve the static address for the Web server on the DHCP Server.

Also, go to Network Connections, right click on the network card that has the static IP address and click properties. Go to the TCP/IP  Properties, click on Advanced and ensure there is only one IP address there.

As there is not much information to play with, I can suggest this at this time, if it doesn't work, I would appreciate some more information on the number of cards and any other errors you receive.
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Author Comment

by:CecilAdmin
ID: 16861492
I'll try out the DHCP reservation...

There is only 1 IP address there.

There are two network cards, but only 1 is plugged in and enabled.
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Expert Comment

by:technologyworks
ID: 16861617
Any other services on that machine (like VPN) that would assign another IP?
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LVL 13

Expert Comment

by:prashsax
ID: 16861812
Can you find out what does this incorrect IP points to.

Does it pings. If the incorrect IP pings, then try and find which machine is doing it.

One more thing, you can try is to look the mac address of the machine in DHCP lease. See which MAC address has been assigned that incorrect IP address.
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LVL 13

Assisted Solution

by:prashsax
prashsax earned 675 total points
ID: 16861861
Does this server has RRAS service running.

It also takes IP from DHCP server for Remote Access..
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Author Comment

by:CecilAdmin
ID: 16863428
Neither VPN connections are installed, nor are RRAS services enabled or running.

When DNS picks up the record with the incorrect DHCP address of the web server, ping does not reply.  

Even when the static DNS record exists, the DHCP address that the DNS eventually picks up in DNS does not ping.
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LVL 13

Expert Comment

by:prashsax
ID: 16863977
Set up your DNS server for Secure Updates only.

This would prevent any rogue system from polluting your DNS.



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LVL 12

Expert Comment

by:Imtiaz Hasham
ID: 16865468
When the incorrect IP is picked up, try running a reverse DNS query. On command prompt, type ping -a <ip address> and pass the results to us, please. The results should have a name such as computername.domain..

Please advise when you have captured the MAC address and given it a DHCP reservation.

Regards,

Imtiaz
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LVL 6

Assisted Solution

by:cbromley33
cbromley33 earned 150 total points
ID: 16867618
You can also tell your server to not update DNS as well.. which should stop the DNS record from changing after you 'fix' it..  But you still need to figure out why that address is being assigned to the webserver.  Have you disabled the other network card on the webserver?  Also, have you checked the 'static' settings on the web server lately to see if they haven't been changed by some accidental click, or annoying patch?
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Author Comment

by:CecilAdmin
ID: 16945908
Not exactly sure which one of these fixed the problem, but this is no longer an issue.  I'm just going to split the points for all who participated...
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Author Comment

by:CecilAdmin
ID: 16945953
I assisted the wrong answer for prashsax...  The assist should go to this post:

Set up your DNS server for Secure Updates only.

This would prevent any rogue system from polluting your DNS.

If one of the forum mods would fix this, I apologize for the confusion.  Thanks for all your help!
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