Why do IP address conflicts occur on an AC? What measures should be taken in this case

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An IP address conflict occurs when two users in a LAN are allocated the same IP address. IP address conflicts are caused by errors in address allocation. For example, a client's IP address has been released using a Release packet or the reset ip pool command or because the lease has expired. However, the AC does not notify the user that the IP address has been released. The DHCP server then allocates this IP address to another client. This client pings the IP address and receives a reply, so it sends a Decline packet to the DHCP server. The server sets this IP address to conflicted state.

When an IP address conflict occurs, run the reset ip pool { interface pool-name | name ip-pool-name } { start-ip-address [ end-ip-address ] | conflict } command on the DHCP server to release the conflicting IP address.

Other related questions:
What can I do if an IP address conflict occurs
Use either of the following methods: Assign a new IP address to the endpoint as follows: From the remote controlled UI, choose Settings > Network > IP and modify the settings of Local IP address. Assign a new IP address to the specified network device.

What measures should be taken when an AP fails to obtain an IP address using DHCP
Perform the following steps to locate the fault: 1. Check whether the AP is configured to obtain an IP address using DHCP. 2. Check whether the Layer 2 link between the AP and DHCP server is working properly. 3. Run the display ip pool name ip-pool-name used command on the DHCP server to check whether the AP has obtained an IP address.

How to resolve DHCP IP address conflict on S series switch
For S series switches (except S1700 switches), if IP addresses in a DHCP address pool have been configured for clients but have not been excluded from the address pool, the IP addresses may be allocated to other clients, resulting in IP address conflicts. For details about how to locate and rectify the IP address conflict problem, see "The IP Address Obtained by a Client Conflicts with the IP Address of Another Client" in Configuration Guide - IP Service.

IP addresses conflict in the address pool of a WLAN device
An IP address conflict occurs when two STAs on a LAN are allocated the same IP address. For example, a STA's IP address has been released using a Release packet or the reset ip pool command, or because the lease has expired for 3 days. However, the AC does not notify the STA that the IP address has been released. The AC then allocates this IP address to another STA. This STA pings the IP address and receives a reply, so it sends a Decline packet to the AC. The AC sets this IP address to conflicted state. You can run the reset ip pool { interface pool-name | name ip-pool-name } { start-ip-address [ end-ip-address ] | conflict } command to release a conflicting IP address.

What measures should be taken when an AC fails to respond to the discovery packet sent by an AP after the AP obtains an IP address
Perform the following steps to locate the fault: - Check the AP authentication mode, blacklist, and whitelist. a) If the AP authentication fails, modify the configuration so that the AP can pass the authentication. b) If the AP authentication succeeds, go on with the following steps. - Check packet statistics on the AC to check whether the AC has received the Discovery packet (assuming that only one AP is connected to the AC). a) If the AC has received the Discovery packet, check whether the CAPWAP module processes the Discovery packet incorrectly. b) If the AC has not received the Discovery packet, check whether a source interface or source address is configured for the AC.

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