Helping people with computers... one answer at a time.
Two computers should never have the same IP address if they're on the same network. If they do, results are unpredictable.
What happens if two computers have the same IP address?
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An IP address uniquely identifies every computer on the internet.
The key word there is unique.
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If two computers on the same network have the same IP address ... well, the results are unpredictable. It depends on how all the other equipment on the network handles the problem. In general it could be as bad as both machines not being able to communicate at all. More likely only one will not be able to, or perhaps there will simply be intermittent problems on both.
In short: don't do it.
Article C2262 - January 18, 2005
Leo A. Notenboom has been playing with computers since he
was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed.
After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers
to common computer and technical questions. More about Leo.
I had an error message come up earlier that said another device on the network had the same IP address, and that I should contact the network administrator. Is this just because, being a home network, there are 3 computers on the network, or is it something I should be worried about?
Posted by: Tom at August 16, 2011 3:52 PMboth of my computers on the same network have the same ip address. i have an airport extreme, a macbook pro and a dell w/xp.
How do I get them to have separate ip addresses so i can utilize remote desktop?
Posted by: WM at August 17, 2011 5:39 PMcan 2 computers have the same ip address, i m having a problem where sumone is using ma IP address and trying to play tricks with me........need urgent help......
01-Nov-2011
Posted by: priya jainani at November 1, 2011 6:30 AM
We have our router and modem connected to my desktop which I only use a hour or so a day if then. The rest of the time I use my laptop. My daughter and son in law all have laptops also. We haven't had any problem until recently when my daughter bought a new lap top and gave her old one to my grandson (here in the same house). At the same time she bought him a Xboc Kennect. Now if I am using my desktop everyone else has a problem getting internet on their computers. We have to reset the modem and router, turn off my desk top and then reboot our laptops computers. The notice that comes up says it can't find the iP address. Is there a way to fix this so we can all use the laptops and I can still sign on to my desktop if I need to without making everyone else go offline?
Posted by: Nancy Bolin at December 14, 2011 4:00 PM@Tom - I remember in my university days we were alloted download quotas and to bypass once we reached out quotas we scanned for MAC addresses cloned them on our pc and used up the other person's quota. using this method the DHCP would think we are the same device and say "did'nt i give you 192.168.x.x ip" and our machines would say "*shrug* I guess so we must've forgotten cani use it now?"DHCP"Sure" a few minutes later "IP conflict exists on this network please fix the problem". Now i am not saying that there might be someone cloning your MAC but for some types of wireless and wired networks it is possible to compromise them by this method. Also this method is used by some malware, though it is pretty rare to find.
@WM ensure your device is set to allow a whole range of devices it might be that your device has a range of only two ip addresses which it is trying to share between itself and two devices.
@Nancy your problem might also be the number of devices that can be assigned an address and time of expiry. so what i can see happening is that your router has 10 addresses to share and you desktop being wired gets one for sure. the other devices get their ip's expired and try to renew but the DHCP is unable to resolve this problem. you reboot the router the previous cache is cleared and the problem is temporarily resolved. Please ensure your router has enough addresses to assign usually under web management DHCP options you will find a range that is allowable for your router.
Posted by: Morpheus Exegis at January 4, 2012 2:00 PM