Problem: Computers Do Not Keep Their Assigned IP Address

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Problem

At some schools, computers in computer labs do not consistently receive their assigned IP addresses. Even though a MAC address and an IP address are manually entered in the computer object, the DHCP server still assigns these IP addresses to other devices.

This leads to the impression that the IP address is reserved, while in practice it is reused by DHCP.

Root Cause

The IP address entered in the UMC Computer Module is not a DHCP reservation.
This setting is mainly used for LDAP and DNS consistency.

The DHCP server does not consider this entry when assigning IP addresses. Therefore, the IP address can be reassigned to another device.

Solution

To ensure that a computer always receives the same IP address, a DHCP reservation must be created.

Follow these steps:

  1. Keep the MAC address and the desired IP address entered in the Computer Module.

  2. Open the DHCP Module and create a reservation:

    • Enter the fixed IP address in the field “Fixed IP Addresses”.
    • Enter the MAC address in the field “Address”.

This DHCP reservation uses the MAC address as a unique identifier and ensures that the DHCP server always assigns the specified IP address to the correct computer.
After this configuration, the IP address will no longer be reassigned.

For more information, see the following documentation sections: