Finding IP Address With Only MAC Address Given

There is a desktops replacement exercise going on. The IP address assigned to the user's existing desktop will be used for the new desktop. At times, the outsourced computer technicians wil request us to change the MAC address of the reserved desktops in the DHCP server without providing any IP address and DHCP scope. The only information given were the MAC address of the new desktop and the MAC address of the user's existing desktop. This make our job of modifying the information of a reserved desktop rather difficult.

In order to find the IP address of the reserved desktop using the MAC address of the user's existing desktop, the below command need to be issued at the command prompt:

Netsh dhcp server dump | find /I”00237db98ab4” > c:\reserved.txt

The output c:\reserved.txt will contain information for a reserved desktop whose MAC address matches 00237db98ab4:

DHCP Server 128.155.1.29 Scope 128.248.0.0 Add reservedip 128.248.2.44 00237db98ab4 “zwen. KANDTI.com.sg” “Zhang Wen’s PC” “BOTH”

IP address reserved: 128.248.2.44
MAC address: 00237db98ab4
Reservation name: zwen.KANDTI.com.sg
Description: Zhang Wen’s PC
Support types: BOTH (i.e. DHCP and BOOTP)

From the output, we know that the desktop reservation can be found under the DHCP scope 128.248.0.0 with IP address 128.248.2.44.