In ECET 2026 Computer Networks (CN), network topologies are important basics. Questions are mostly theory-based but sometimes include formulas related to links and communication lines.
📘 Concept Notes
🌐 What is a Network Topology?
- Network topology = physical or logical arrangement of nodes (computers) and communication links (cables, wireless).
- Determines how devices are connected and how data flows.
⚙️ Types of Network Topologies
- Bus Topology
- Single backbone cable.
- All devices connected to the same line.
- Failure of backbone → whole network down.
- Example: Early Ethernet.
- Star Topology
- Central device (hub/switch) connects all nodes.
- Easy to troubleshoot, scalable.
- If central device fails → network fails.
- Example: Modern LANs.
- Ring Topology
- Each device connected to two neighbors, forming a ring.
- Data travels in one direction (unidirectional) or both (bidirectional).
- Failure in one node can affect network unless dual ring is used.
- Mesh Topology
- Each node connected to every other node.
- High reliability, no single point of failure.
- Expensive due to many connections.
- Example: WAN, Internet backbone.
- Tree Topology
- Combination of star + bus.
- Hierarchical structure.
- Used in large networks like universities.
- Hybrid Topology
- Mixture of two or more topologies.
- Example: Star + Ring in corporate networks.
🔢 Formulas
- Number of links in a Mesh topology (full mesh):
where
= number of nodes. - Number of links in Star topology:
Number of links in Ring topology:
Bus topology:
Always uses 1 backbone cable.
📐 Example
If 6 computers are connected in:
- Star:
- Ring:
- Mesh:
🔟 10 Expected MCQs – ECET 2026
Q1. Which topology uses a single backbone cable?
A) Star
B) Bus
C) Ring
D) Mesh
Q2. Failure of central hub affects which topology most?
A) Mesh
B) Star
C) Ring
D) Bus
Q3. In mesh topology, number of links with 10 nodes is:
A) 45
B) 90
C) 20
D) 55
Q4. Ring topology is:
A) Highly reliable
B) Centralized
C) Each node connected to two neighbors
D) Uses one backbone cable
Q5. Example of modern LANs is:
A) Ring
B) Mesh
C) Star
D) Bus
Q6. Tree topology is combination of:
A) Bus + Mesh
B) Star + Bus
C) Star + Ring
D) Mesh + Ring
Q7. Which topology is most fault tolerant?
A) Mesh
B) Star
C) Ring
D) Bus
Q8. If 5 nodes in star → number of links = ?
A) 4
B) 5
C) 6
D) 10
Q9. In bus topology, if backbone fails:
A) Only one node fails
B) Whole network fails
C) Two nodes fail
D) None
Q10. Hybrid topology means:
A) Only star network
B) Only mesh network
C) Mixture of two or more topologies
D) Tree structure only
✅ Answer Key
| Q.No | Answer |
|---|---|
| Q1 | B |
| Q2 | B |
| Q3 | A |
| Q4 | C |
| Q5 | C |
| Q6 | B |
| Q7 | A |
| Q8 | A |
| Q9 | B |
| Q10 | C |
🧠 Explanations
- Q1 → B: Bus uses single backbone cable.
- Q2 → B: Star depends on central hub.
- Q3 → A:
. - Q4 → C: Ring connects each node to two neighbors.
- Q5 → C: Star used in modern LANs.
- Q6 → B: Tree = Star + Bus.
- Q7 → A: Mesh has no single point of failure.
- Q8 → A:
. - Q9 → B: Backbone failure → whole bus network fails.
- Q10 → C: Hybrid = mixture of multiple topologies.
🎯 Why Practice Matters
- Topology questions are direct, easy to remember, and repeated in ECET.
- Link formulas are scoring.
- Easy 2–3 marks for CSE aspirants.
