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One customer laptop reports ....  duplicate IP address on the network (or some similar error)

Posted on 2013-10-23
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Last Modified: 2013-10-24
IP conflict error. Simple home setup with a few users, nothing fancy. 1 pc, 2 laptops


Im going on site soon.

I dont think its a fixed ip address.

What the chances its the router? Im considering swapping it out

I will update the wireless driver.
Anything else to try?

Its either XP or Vista - I think Vista.

Thanks
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Question by:fcek
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8 Comments
 
LVL 9

Expert Comment

by:WebDevEM
ID: 39593849
Hi,

If all of them are using DHCP, not fixed IP addresses, sometimes it's as simple as having it request another address from the router.  I had a power outage at my house last week (same scenario - home wifi, DHCP, just a few machines) and one of the laptops came up with a duplicate IP address.  

I launched a command prompt, and did
ipconfig /release
ipconfig /renew
and it worked fine.  A reboot would have done the same thing, but that laptop was serving our network drive to the rest of the house so I didn't want to interrupt that service.

Hope this helps!

WebDevEM
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LVL 22

Assisted Solution

by:CompProbSolv
CompProbSolv earned 1000 total points
ID: 39594798
Unless my memory is wrong, the error message should show you the MAC address of the conflicting device.  You can check that on the other devices to see which is causing the conflict.
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Author Comment

by:fcek
ID: 39595768
Wireless connection.  Its been happening for months to the end user.
So a reboot isnt going to cure it.
if an IPConfig release / renew doesnt - what will?
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LVL 9

Accepted Solution

by:
WebDevEM earned 500 total points
ID: 39595947
If a release/renew doesn't fix it, then most likely that machine is playing by the rules and another on the network may be hard-coded to the IP address that this laptop currently has.  In that case, CompProbSolv's approach will help.  

List all the devices on the network... laptops, desktops, printers, tablets, phones... anything that connects to the WiFi.  Find their MAC address and compare it to the MAC in the error message if you can get that.  If you can get an iPhone or iPad on the network something like iNet Network Scanner can save you a lot of time by scanning for everything on the same network it is on, telling you the IP address and MAC.  (The paid version does more, but the free one should do just fine in this case)  Even if it doesn't find the machine you're looking for (which may happen because of the conflict on that IP address), it can help by eliminating the others.
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LVL 22

Assisted Solution

by:CompProbSolv
CompProbSolv earned 1000 total points
ID: 39596022
If you can consistently get the message, such as after ipconfig /release ipconfig /renew, then unplug each end device (printer, computer, etc.) one at a time and repeat the test.  When you don't get the error, the last disconnected device is likely the culprit.
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LVL 93

Expert Comment

by:nobus
ID: 39596765
you can do a power off/on cycle on the router
that can fix many issues
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LVL 10

Assisted Solution

by:ampranti
ampranti earned 500 total points
ID: 39598212
The dupliacate Ip address applys to Local Lan.
Try:    ipconfig /release &     ipconfig /renew
If problem persits, clear dhcp bindings from router or restart router.

To prevent the problem re-appearance, reduce the "lease time".
Probably dhcp pool is full.

Check if an other device in the place has the same IP:
Change the laptop's IP and ping the old IP. Is any devices replying to pings?

Otherwise, someone is connecting to your Wifi!
Change the password (I hope is WPA2-PSK and not WEP) , and check if happens again
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Author Closing Comment

by:fcek
ID: 39598744
The location was a small shop, I said home as it appeared to be a very simple setup.

I connected another router and when I connected only a PC and a mystery cat5 cable the error occurred.

This ruled out all wireless devices.

I found out that the mystery cable was going to a credit card machine.
It was bullying the other clients I think.

I reserved an IP address for it high in the range via the router and problem solved !

Thanks for everyones opinion as it guided me to the answer.

Another case solved.
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