IP Address Conflict

What is an IP address?

An Internet Protocol (IP) address is a logical address or a numerical identification assigned to a device participating in a computer network. This unique identification basically names the device, locates it, and defines the route on how to get there.

An IP address may be private, for use in a Local Area Network (LAN), or public, for use on the Internet or other Wide Area Network (WAN). It is usually assigned by a statically determined system administrator or assigned by another dynamically determined device on the network.

What is an IP Address Conflict?

IP address conflicts happen when two computers on the Internet or in a Local Area Network have the same IP address. An IP conflict render either one or both of the computers unusable because of intermittent connection or it cuts off the connection all together.

How Does an IP Address Conflict Happen?

An IP address conflict may happen through any of the following:

  • A system administrator statically assigns an IP address to two computers in a Local Area Network;
  • A system administrator statically assigns a computer with an IP address within a LAN’s DHCP range, while a LAN DHP server automatically assigns the same address;
  • Multiple computers are automatically assigned with the same dynamic address due to a malfunction in the DHCP’s server;
  • Two customers are accidentally assigned with the same dynamic or static address by their Internet service providers (ISP);
  • A malfunction caused by a system coming back online from an extended period in stand-by or hibernate mode;
  • A computer configured with multiple network adaptors; or
  • A system administrator connects two ports of a network switch or a router to each other.

How Do You Recognize an IP Address Conflict?

Most Microsoft Windows computers will show this pop-up error message when attempting to set-up a static IP address already active in a local network:

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

Conversely, Microsoft Windows computers with dynamic IP conflicts will receive a balloon error message in the taskbar once the Operating System detects it. It will display the following message:

“There is an IP address conflict with another system in the network.”

A similar message may appear in a pop-up window in computers with older versions of Microsoft Windows:

“The system has detected a conflict for IP address…”

The same message may appear in Mac or Linux computers.

How is an IP Address Conflict Resolved?

IP address conflicts are most likely to resolve themselves in DHCP environments as the systems request for valid addresses. However, this process may take a while or it may not even resolve itself.

The following procedures may help resolve IP address conflicts:

  • Computers with statically assigned IP addresses can resolve this issue by ensuring that each local host is configured with a unique IP address.
  • Computers with dynamically assigned IP address can resolve the issue through the following steps:

1. Release and renew its IP address by manually entering IPCONFIG /RELEASE and IPCONFIG /RENEW from a command prompt.

2. If the conflict still persists, the system may have been issued with the same address and another system in the network may be the source of the problem. The offender can be traced by checking the System Log within the Windows Event Viewer.

START | CONTROL PANEL| ADMINISTRATIVE TOOLS| EVENT VIEWER| and look for a DHCP ERROR ENTRY.

3. Look for a DHCP ERROR ENTRY by running IPCONFIG/ ALL on a Windows system or by checking the label on the back or underside of a non-PC device. The DHCP error entry will list a network address that can be used to find the conflicting device.

Releasing and renewing an IP address or starting the other device should resolve the conflict. However if the problem persists, restart the router to reset the DHCP server and force all systems to request for new IP addresses.

  • Systems experiencing chronic IP address conflicts with no traceable cause should consider updating the router with its most recent firmware.

For more information on IP Address Conflict read:

  • IP Address Conflict