Exam Code 642-801 BSCI

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Q2. Which of the following represent a typical three-layer hierarchical internetworking model? [Choose 3].

A. Core layer                     B. Optimization layer                     C. Distribution layer                     D. Access layer

Ans: A, C, D

Explanation:  

The Three layer approach:
            1. Core layer: The primary function of Core layer is to provide an optimal and reliable transport structure. The core layer is the backbone network of the entire internetwork and may include LAN and WAN backbones. Core layer usually consists of fully redundant paths with technologies such as FDDI, Fast Ethernet, and/ or ATM.
            2. Distribution layer: The primary function of this layer is to provide access to the internetwork as well as to the servers. Distribution layer sits between the Core layer and the Access layer. The policies such as ACLs are implemented at the distribution layer. Distribution layer is also known as workgroup layer.
            3. Access layer, also known as desktop layer controls as to how the users access the resources on internetwork. 
            In real world, the layers may be overlapping, in the sense, that a single device may be functioning at both Access layer as well as distribution layer. This is true for even Core layer.

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