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IP Address Conflict

Each computer on a network must have a unique IP Address.
You can think of an IP address a bit like a phone number.
  1. IP Addresses are assigned by your router, whereas a phone number is assigned to you by the phone company.
  2. An IP Address assigned by a router is only leased for a period of time, typically, this about 24
    hours. If the IP Address is no longer in use when the lease is up, it gets recycled, and the router views that IP
    address as available for reassignmnet.  Similar to the phone company giving a new customer a prior customer’s
  3. A computer requests an IP from the router when it first connects to the network. This is typically during the boot-up process, or when you first establish a wireless connection.
  4. When a laptop or netbook goes into a sleep or hibernate mode, many of the system settings are saved in
    memory or onto the hard drive. This includes the IP address which was assigned to it. If the computer in question remains in this state long enough, it is possible for the IP address lease to expire, get recycled by the router as it does not see the computer while it is in this low power state, and another computer gets assigned that IP address. Therefore, when the computer is awakened,retaining its stale IP address, a conflict is noted.


Friday afternoon, nobody has used the wifi for a while, and User A boots up her computer. When it connects to the wireless, the router assigns the IP address, when User A is done using it, she closes the lid placing the computer in standby.


Saturday afternnon, 24 hours has gone by and the router is going to make a decision to either renew the lease, or expire it for IP  Seeing no recent activity coming from this IP address it is recycled.


Saturday evening, User B connects to the wireless, and the first number available in the pool is


A little later Saturday evening, User A opens up her laptop, awakening it from standby, and connects
to the network with it’s stale settings of IP Both systems likely alert their respective users about the conflict, and also likely a loss in Internet activity.  


Typically, it will be the computer returning from the low power state which needs to have the repair run on it. In the above scanrio, the IPAddress on her computer is stale, and needs to be reassigned by the router. I believe this can be accomplished by clicking on the message, and then choosing to repair the connection, which will request a new IP address from the router. When this request is processed, the router will assign the next available number Running the repair from your computer in this scenario will not resolve the situation, as the router knows that the IP address in question has been assigned to your computer and will reassign the same one.