Explanation/Reference:
Section: Design Methodologies Explanation
Explanation:
Most likely, you would route cables from a server room to workstations first when using the bottom-up network design approach. This action would fall into the Physical layer of the Open Systems Interconnection (OSI) reference model. In contrast to the top-down approach, the bottom-up approach begins at the bottom of the OSI reference model. Decisions about network infrastructure are made first, and application requirements are considered last. This approach to network design can often lead to frequent network redesigns to account for requirements that have not been met by the initial infrastructure.
You would analyze the company application requirements during the initial phase of the top-down network design approach, not the bottom-up approach. The top-down network design approach is typically used to ensure that the eventual network build will properly support the needs of the network's use cases. For example, a dedicated customer service call center might first evaluate communications and knowledgebase requirements prior to designing and building out the call center's network infrastructure. In other words, a top-down design approach typically begins at the Application layer, or Layer 7, of the OSI reference model and works down the model to the Physical layer, or Layer 1.
The top three layers of the OSI reference model-which are the Application layer, Presentation layer, and Session layer-should be analyzed in order to determine the design requirements. The infrastructure that is needed for the Transport layer, Network layer, Data Link layer, and Physical layer is thus determined by this analysis.
You would not license operating systems (OSes) to host network services or configure switches with virtual LANs (VLANs) first when using the bottom-up design approach. Licensing OSes to host network services would most likely be performed in the Transport layer, or Layer 4, of the OSI reference model. Configuring switches with VLANs would most likely fall in the Network layer, or Layer 3, of the OSI reference model.
Reference:
CCDA 200-310 Official Cert Guide, Chapter 1, Top-Down Approach, pp. 24-25 Cisco: Using the Top-Down Approach to Network Design (Flash)