What Is an IP Address Conflict?

Multiple causes make IP address conflicts difficult to troubleshoot

An IP address conflict occurs when two communication endpoints on a network are assigned the same IP address. Endpoints can be PCs, mobile devices, or any individual network adapter. IP conflicts between two endpoints normally render either one or both endpoints as unusable for network operations.

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How IP Address Conflicts Happen

Two computers or other devices can acquire conflicting IP addresses in several ways:

  • A system administrator assigns two computers on a local area network with the same static IP address.
  • A system administrator assigns a computer a static IP address within the local network's DHCP range, and the local DHCP server assigns the same address automatically.
  • A malfunction in the network's DHCP server allows the same dynamic address to be assigned to multiple computers automatically. This can occur when a mobile device is put into a hibernate mode and then awakened later, for example.
  • An internet service provider accidentally assigns two customers the same IP address either statically or dynamically.

Other forms of IP conflicts can occur on a network. For example, one computer may experience an IP address conflict with itself if that computer is configured with multiple adapters. Network administrators may also create IP conflicts by accidentally connecting two ports of a network switch or network router to each other.

How to Recognize IP Address Conflicts

The exact error message or other indication of an IP conflict varies depending on the type of device affected and the network operating system it runs.

On many Microsoft Windows computers, if you attempt to set a fixed IP address that is active on the local network, you receive the following pop-up error message:

The static IP address that was just configured is already in use on the network. Please reconfigure a different IP address.

On newer Microsoft Windows computers that have dynamic IP conflicts, you receive a balloon error message in the Taskbar as soon as the operating system detects the issue:

There is an IP address conflict with another system on the network.

Sometimes, especially on older Windows computers, a message similar to the following may appear in a pop-up window:

The system has detected a conflict for IP address...

How to Resolve IP Address Conflicts

Try the following remedies for IP conflicts:

  • For networks where IP addresses are fixed, confirm that each localhost is configured with a unique IP address.
  • If the computer has a dynamically assigned address, release and renew its IP address to work around IP address conflicts.
  • If you believe the broadband router has a faulty DHCP server that causes IP conflicts on the home network, upgrade the router firmware to resolve the problem.