What are the factors that must be considered before making a choice for the topology ?

The factors that must be considered before making a choice for the topology are as follows:

1. Cruciality of Work — How crucial the continuity of work is a very important factor. For instance, military networks must not fail at any cost thus fully connected topology is preferred for military networks.
2. Cost — Keeping in mind the budget, we should decide about a topology. A linear bus topology network may be the least expensive way to install a network. Fully connected is the most expensive way of creating a network.
3. Length of cable needed — Sometimes, length of cable must be saved. The linear bus topology network uses shorter lengths of cable.
4. Future growth — If a network has to grow in future, then the topology must support expansion. With a star topology, expanding a network is easily done by adding another concentrator.
5. Communication Media — Sometimes, difficult terrains like hilly areas do not allow use of regular cables. For such conditions, linear bus topologies are not possible. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.