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Random IP Addresses within DHCP Drop Packets When Accessing Resource At Remote Location

Posted on 2007-11-20
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Last Modified: 2012-08-14
I have a Windows 2003 Domain that is supported by two DCs that each also are configured as DHCP Servers which lease IP Addresses to my 300 Dell Optiplex Client Machines. The addresses they lease are 172.16.2.x & 172.16.3.x
I have recently noticed that some clients that receive an IP Address of 172.16.3.x are unable to access HTTP resources properly at my parent companies site. When try they try, page either partically loads or they get the page cannot be displayed message.
What is even stranger is that the problem seems to travel with the IP Address. In that when the lease expires and it is assigned to a new client, then that client has the problem accessing the resource. So it does not appear to be a hardware problem.
I have looked at all the switches and routers concerned and they appear to be functioning as they should. I cannot notice any CRCs or alarming Retransmits.

I have used ethereal to monitor the network but again cannot see anything that i would deem relevant.
Can some assist me on this matter.
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Question by:biggiesmallzz
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by:tedf
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Are your DHCP servers and clients on the same or different subnets?  What mask and default router is being issued by each DHCP server?
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by:biggiesmallzz
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Both DHCP Servers are on the same subnet and use the same router as the default gateway.
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by:tedf
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Is it one specific address out of 172.16.3.x, or several?  Are there any left over or out of order firewall statements anywhere between the source and the destination?  Does this only happen on addresses out to the parent coompany (i.e. can the affected machine reach interior addresses on the same or different subnet, or addresses other than the parent company but outside the local network)?  If all of the Dell clients are on the same subnet, are they getting a mask of 255.255.255.0 or 255.255.254.0?
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by:biggiesmallzz
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1. Bizarrely only specific addresses out of the 172.16.3.x address range are affected. The addresses are not sequential either.
2. The firewall does not treat the rouge ip addresses differently from working ip addresses. The rouge ip addresses are also not malformed on their way to the firewall.
3. This problem only happens to addresses on their way to the parent company.
4. These affected machines can reach interior addresses on the same subnet.
5. Addresses other than the parent company can be reached.
6. All clients whether they have a 172.16.3.x or 172.16.2.x address have the same subnet which is 255.255.240.0

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biggiesmallzz earned 0 total points
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After some very painfull discussions with the third party who maintanis the managed routers, it became clear that the root cause of the problem was with the routers after all.
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