A distributed database system refers to a collection of several logically related databases which are physically scattered in different computers or sites over a computer network (Kossmann, 2012). It is a logical union of all the sites and the distribution is hidden from the users. Therefore, the distributed database users have the notion that the whole database is local except for the communication delays between the sites. The distributed approach is preferred over a centralized database system for various reasons, such as workload sharing (Ashdown and Kyte, 2011). The design of responsive distributed database system is a major concern for information system experts. This applies mostly to high bandwidth networks where latency and local processing are the most significant factors in query and update response time. In a distributed relational database system, the records are geographically distributed. Therefore, the processing of a scattered query is made up of the three phases. These phases are the local processing phase, the reduction phase, and final processing phase. In their study, Upadhyayaand Lata (2012) noted that the local processing phase constitute of local processing operations such as selections and projections. The reduction phase on the other hand uses a sequence of reducers such as semi-joins and joins to condense the size of relations. Lastly, the final processing phase sends all resulting relations to the assembly site where the final result of the query is constructed. Another major concern in a distributed environment is security. The rationale of distributed database security is to deal with the protection of data from people or, software having malicious intension (Kose, 2013). In his study, Batra (2013) established that distributed system has four main security components, namely security authentication, authorization, encryption, and multi level access control. Media access control address (MAC address) provides a unique machine dependent feature that can be used to uniquely identify network devices and therefore is deemed ideal to be used in this research for authenticating users hence offering optimum access control to a distributed environment. 2. Related Work The goal of distributed databases query security is to ensure that only legitimate queries are processed by the distributed database systems. This will lead to improved processing time and quick responses to the lawful users. Alavi (2014) explains that distributed database management systems run on top of an underlying operating system. These operating systems provide the security allied with databases. Classical operating system security features involve memory and file