IP address collision occurs when two or more devices are assigned the same IP address on the same network. This situation will cause a certain amount of conflict in the network connection, because each device must have a unique IP address in the network for normal communication operations.  When  IP  address  collision  occurs,  the  device  may  not  be  able  to  connect  to  the network, resulting in unstable network connection status.

Reasons for IP address collision:

1.  Manual configuration error:

When the  network administrator  manually assigns the same  IP address to multiple (greater than one) devices, it will lead to IP address collision and the devices cannot connect to each other.

2. DHCP server problems:

DHCP servers may assign duplicate IP addresses to different devices due tomisconfiguration or software malfunctions, which can also cause IP address conflicts.

3.  Mixing  of  static  and  dynamic  IP  addresses:  

If  some  devices  in  the  network  use  static  IP addresses and other devices  use dynamic  IP addresses, and the  IP address  ranges of the two overlap,a collision may occur.

4. Network device reboot or factory reset:

Some devices may try to use the previous IP address after rebooting or factory reset, which may cause conflicts.

5. ARP cache not updated:

In some cases, the ARP cache of the device may not be updated in time, resulting in IP address conflicts.

Solutions to IP address conflicts:

1. Automatic Repair:

Some operating systems can automatically detect IP address conflicts and try to fix them, such as requesting a new IP address via DHCP.

2. Manually check and modify IP addresses:

①Check the  IP configuration of the conflicting devices and make sure that the IP address of each device is unique.

②Modify  the  static   IP  address  or   reconfigure  the   DHCP  range  to   ensure  that  duplicate addresses are not assigned.

3. Reboot the network device:

Reboot  routers,  switches   and  other  network  devices,  and  force  the  ARP   cache   and  DHCP allocation table of the device to be updated.

4. Isolate problematic devices:

Gradually  disconnect  network  devices,  determine  the specific  device that  has  a  collision,  and then reconfigure its IP address.

5. Update the DHCP configuration:

Make sure that the IP address allocation range of the DHCP server does not overlap with any static IP address, and configure the appropriate rental period time.

①Back  up the configuration files of the  DHCP server so that the operation can be resumed in case of failure.

②Download the latest compatible DHCP server software from the official website.

③Stop the running DHCP server.

④Install the latest DHCP server.

⑤According  to the  updated  content,  refer to the  previous  backup  configuration,  modify  the

existing configuration and start.

⑥Finally test whether it can be used.

Precautions against IP address conflict:

1.  Plan  IP  address  allocation:  

Make  a  detailed  IP  address  allocation  plan  to  avoid  overlapping static and dynamic IP address ranges.

2. Use DHCP reservation:

Set IP address reservation on the DHCP server for specific devices to ensure that these devices always get the same IP address.

3.  Monitor the network regularly:  

Use  network monitoring tools to scan and check  IP address assignments in the network regularly to find and solve potential problems in time.

4. Record and document the configuration:

Record the IP address configuration of all the devices in the network in detail and keep the documentation up to date so that problems can be quickly found and solved when they occur.