My system has been assigned an IP that I liked from a dhcp server.

I have manually given that IP address to my system. Now I am frequently getting an error that someone else has taken my IP address. So my questions are:

  1. While I am using that IP, how this IP can assigned to someone else? Note: this happens only when I use this IP on my macbook. This never happens when I use my windows pc.

  2. How can I assign an IP address to my system so that nobody else can take that IP from the dhcp server?

It's very irritating when I am in the middle of a browsing session and suddenly an error pops up that somebody else has taken my IP


case 1: I have two systems. system A(macbook pro) and system B (windows pc). I have given x:x:x:x ip address to system A and now I am giving same ip to system B. system A macbook pro will give error that your ip has taken.

case 2: I have two systems system A (windows pc) and system B (another windows pc). I have given x:x:x:x ip address to system A and now I am giving the same ip address to system B. Now system B will give error ip conflict. I think this is more appropriate error.

I want the same thing for case 1.

  • This is more of a superusers question (even though the mac only thing is kind of irritating). – miceterminator Sep 1 '12 at 19:55
  • i have asked here because i have this problem only in my macbook pro. – Vivart Sep 1 '12 at 20:03

You might want to check out your routers web interface. Usually you can assign a preferred (or probably obligatory) IP-Address to a specific Mac Address in this case the mac adress of your Laptop. (you might want to read the wikipedia article about mac adresses as it explains a lot more and might be available in your native language)


Your DHCP server is giving out the IP address you manually assigned to your mac computer to another computer.

If you manually assigned the same IP to your windows computer the same thing could happen, but it depends on how the DHCP server is configured.

The only way to solve this issue is to put in a "reservation" on the DHCP server for your computers and the IP you like. As is pointed out this is done by matching the IP to your network adapter mac address.

You cannot resolve this on your computers, you have to have access to the DHCP server and the DHCP scope to resolve this. If you don't you will have to send a request to your IT department or whoever has access to the DHCP server.

Once the reservation is in place on the DHCP server you can still assign the address manually to both your mac and windows computers but it just means that nobody else will be able to get the same address and you will not get the conflict.

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