Windows IP address conflict detected...

[andyoxon]

Anyone know about what this is all about..?

Two laptops,and wifi printer on in house, but why the error..?  Some patchy internet connection over the last few days too.

[Kim]

Assuming that IP addresses are being allocated by a DHCP server on the router, then it shouldn't happen.  Usual cause is a machine with a statically configured address that's within the DHCP server's pool, which can work fine for ages before causing a problem.  Or the DHCP server's on the blink (entirely possible that rebooting the router has caused it to lose its table of allocated leases).  Or someone's trying to h4xx0r onto your network.  Or something.

If the system event log tells you the MAC address of the conflicting device, that should give you a clue.

[Polar Bear]

Strangely I also had this crop up yesterday.   I simply ignored it.

[andyoxon]

Had a look at the event log...



Any ideas?

Log Name:      System
Source:        Tcpip
Date:          02/06/2012 00:05:23
Event ID:      4199
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      Laptop-M90
Description:
The system detected an address conflict for IP address 192.xxx.x.x with the system having network hardware address xx-xx-xx-F2-F8-24. Network operations on this system may be disrupted as a result.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Tcpip" />
    <EventID Qualifiers="49152">4199</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2012-06-01T23:05:23.745005800Z" />
    <EventRecordID>29570</EventRecordID>
    <Channel>System</Channel>
    <Computer>Laptop-M90</Computer>
    <Security />
  </System>
  <EventData>
    <Data>
    </Data>
    <Data>192.xxx.x.x</Data>
    <Data>xx-xx-xx-F2-F8-24</Data>
    <Binary>0000000003002C0000000000671000C0020000000000000000000000000000000000000000000000</Binary>
  </EventData>
</Event>

...and what's a kernel-processor-power warning?  'speed of processor being limited by firmware...`

[Jaded]

Was it asleep? Maybe it thought it had an address, but the address was then given out by the router to another device?

If you can give devices fixed ip addresses, try that for the laptop?

[andyoxon]

Yes, that's true PC could well have been asleep or hibernating...

[tonycollinet]

With most routers you can tell the dhcp server to always give the same IP to the same device. You have to tell it the mac address of the device, and the ip you want it to have.

Solves most of these sort of issues.

[Woofage]

I think "ipconfig /renew" will force the router to assign another address. Quicker than a re-boot.

Otherwise, this:

With most routers you can tell the dhcp server to always give the same IP to the same device. You have to tell it the mac address of the device, and the ip you want it to have.

Our router sniffs the all MAC addresses on the network so you don't have the enter them. See if yours will.

[Kim]

Was it asleep? Maybe it thought it had an address, but the address was then given out by the router to another device?

I'd have thought it would come out of hibernation, notice the clock delta and attempt to renew the expired lease before resuming notjbex operations.  OTOH, it's Windows...

[Feanor]

When starts or resumes, it sees the network connection coming up.
Assuming it is configured to 'obtain an IP address automatically' ( check this ), then it will contact the DHCP server ( usually your router ) and request an IP address ( or permission to continue using the one it has previously got ).
When it's given one, windows then does a 'sanity check' to make sure the address is really free.
This is called 'Duplicate Address Detection'.
( It uses a process called Gratuitous ARP, where it sends out a query on the network for the address.   There should be no response. )
If there is a response, then it throws the error you see.

Either the DHCP server messed up ( unlikely ), or you have something on your network manually set to that IP.
If you need to manually set the IP of something ( like a printer ), then set it to a high number ( eg 192.168.0.200 ) and then make sure this range is excluded from the DHCP server scope.

If you tell us the full MAC address of the offending device, ( xx-xx-xx-F2-F8-24 ) we can probably tell you which device on your network is producing the conflict.

[andyoxon]

Thanks.  Done some checking and the MAC address in the details above is the Xbox 360 console.  The Xbox setting are on automatic for IP address I think.  So any ideas what went on?

[Feanor]

If both devices were indeed obtaining their IP address from the same DHCP server, then that should not happen.
DHCP brain-fart.

I'd shut off the clinet machines, re-start the router to flush the DHCP assignments and then let the various clients start picking up addresses again.

There are some scenarios where this sometimes happens.
Say the Xbox picks up an IP address lease from the server, and is using it.
If the router were to re-start, it would loose it's list of assigned addresses.
If it's DHCP server is a bit basic, it won't perform Duplicate Address Detection before re-issuing the address to another client.
The other client is smart enough to to DAD, and throws the error.