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IP Conflict

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by cg._

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Hello all; I am having a problem with a small network that I need help with, this has happened a few times now where two laptops receive the same IP address from my DHCP server, and it is always the same 2 laptops, I was able to fix this momentarily by excluding the IP address that was in question then both laptops received a different IP but then after a week the same problem occurred, I don't why this keeps occurring with the same 2 laptops it makes no sense to me.
I now have 3 IP addresses excluded from my range because of this problem, the list will eventually get too big unless I fix the problem.

Thanks in advance for your help, if you need any further info please let me know.

CG._

7 replies

by eduardo (pt)

...it's very unlikely that both computers have the same MAC address, unless you have configured that one by yourself. But yes, checking each one of the MAC address is the way to start.

by the scummy one

that one system may be spoofing the MAC address. But if so, then why would it pull a different address if an IP address is disabled?

I am thinking it might be a cloned drive. Run a SID changing tool (SID scrambler) on at least one of the systems.

And to note, after they pick up a new IP address, you should be able to re-enable the previous one.

by robo_dev

Are these wireless interfaces? Got Mobile IP enabled?

Do the users routinely put these PCs into sleep mode and go off-network with them?

Typically a DHCP server sends out a PING before it assigns an address, and if the PC is asleep or off the network, it cannot respond.

If the PCs stay on the network all the time, make sure the power management is setup so the lan interface does not power-down in standby mode.

Make sure the user has not bridged the wirelss and wired ethernet interfaces, or odd things may occur.

by deepsand

Try the "Questions" forum; the "Discussion" forum is for matters of general discussion, not specific problems in search of a solution.

Post problems such as this to the "Question" forum, rather than the "Discussion" forum. There are those who specifically seek out problems in need of a solution, and that's where they go to look for such.

Additionally there are the benefits that:

1) The "Questions" forum provides for your feedback, by way of your being able to mark "helpful" responses as such. This does not necessarily mean that a given response contained the complete solution to your problem, but only that it served to guide you toward it. This is intended to serve as an aid to those who may in the future have a problem similar to yours, so that they might have a ready source of reference available, thereby perhaps obviating the need for them to repeat questions previously asked and answered.

2) The revised TR makes it quite difficult to find both "Discussions" and "Questions" that have not had a fairly recent post, owing to some functions comingling them in the listings. By keeping each type in their respective forums, it is easier for all to find what they are looking for.

by cg._

Thank you guys for your help, the problem was actually that the dchp database was corrupted and therefore giving out the same ip to different computers, after reconciling the dchp database and then verifying it, the problem was solved, and just fo fun I added some reservations to the scope just to make sure that does not happen again.

Thank you all again for your input.

CG._

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