Cisco IP conflict after Windows update

[syrovyivitalii]

Hi everyone, I've encountered an issue with my DHCP server involving IP conflicts. The server is configured with a 90-day lease, and the database agent is working correctly. However, after one of the PCs in my network received a Windows update, its IP address was blocked due to an IP conflict, and the device was assigned a new IP. This is problematic for me because I want the DHCP server to assign IP addresses and keep them stable over a long period, almost like setting them as static.

[liviu.gheorghe]

Hello @syrovyivitalii ,

if you don't configure static bindings in your DHCP server you will most likely face this kind of situation in the future. Even if you configure a very long lease time on your DHCP server the situation you described still can happen.

If it's important for you that the DHCP server assigns the same IP to a PC, configure static bindings in your DHCP server.

HTH

[syrovyivitalii]

Hello,

Are you saying that I need to assign each PC’s MAC address to the specific IP I want them to receive? I'm using VLANs in my office, so what would be the best approach to achieve this?

I found the following method to map a host to an IP, but it doesn’t seem to be working correctly:

ip dhcp pool <pool-name>
host <device-MAC-address> <desired-IP-address>

Any advice would be greatly appreciated!

Best regards,
Vitalii Syrovyi

[liviu.gheorghe]

Yes, that is what I am recommending.

If the DHCP server is configured on a IOS or IOS XE device, then the configuration is as follows:

ip dhcp pool <pool-name>

address <IP address> hardware-address <mac address of PC>

You will have to configure a separate dhcp pool for each VLAN you want to assign addresses.

HTH

[danielbrown8998]

Set DHCP Reservations: In your DHCP server settings, reserve IP addresses for the MAC addresses of the devices you want to keep stable. This way, the DHCP server will always assign the same IP.

Extend Lease Time: Since your lease is set to 90 days, you can further ensure stability by keeping this configuration, as long as devices don't change.