A system and method for determining if DOCSIS-enabled devices (DEDs) connected to an HFC cable network are co-located. Subscriber account data is acquired to determine the DEDs associated with a subscriber account. The MAC address of the DEC is used to obtain the MAC domain to which a DED is assigned and the ranging offset value associated with the DED. An alert is issued if multiple DEDs associated with a subscriber account are associated with different MAC domains. The alert signifies that DEDs associated with the account are not co-located. Where DEDs associated with an account are associated with the same MAC domain, the normalized ranging offset values associated with the subscriber's DEDs are compared to determine if the difference in their values exceeds a predetermined threshold. If the difference in their values exceeds a predetermined threshold, an alert is issued. The alert again signifies that DEDs associated with the account are not co-located.