1. Star Topology
- Structure: Central node (hub or switch) connects all devices.
- Advantages:
- Easy to set up and manage.
- Fault isolation (failure in one device doesn’t affect others).
- Disadvantages:
- If the central hub fails, the entire network goes down.
- Requires more cables.
- Examples: Home or small office networks.
2. Bus Topology
- Structure: Single central cable (backbone) connects all devices.
- Advantages:
- Easy and cost-effective for small networks.
- Fewer cables required.
- Disadvantages:
- Collision of data can occur on the main cable.
- Difficult to troubleshoot.
- Failure of the backbone disrupts the entire network.
- Examples: Early LAN setups.
3. Ring Topology
- Structure: Devices are connected in a circular loop, with each device connected to two neighbours.
- Advantages:
- Equal access to resources (token-passing prevents collisions).
- Performs well under low traffic.
- Disadvantages:
- If one device fails, the entire network may fail (can be mitigated by dual rings).
- Adding/removing devices disrupts the network.
- Examples: Token Ring networks (obsolete now).
4. Mesh Topology
- Structure: Every device is connected to every other device.
- Advantages:
- High fault tolerance (multiple paths for data).
- Reliable and secure.
- Disadvantages:
- Expensive due to the large number of cables and ports.
- Complex setup and maintenance.
- Examples: WANs like the Internet.
5. Hybrid Topology
- Structure: Combines two or more topologies (e.g., star-bus, star-ring).
- Advantages:
- Flexible and scalable.
- Can leverage the strengths of individual topologies.
- Disadvantages:
- Complex design and higher costs.
- Examples: Large enterprise networks.
Key Comparison Table
| Topology | Fault Tolerance | Cost | Use Cases |
|---|---|---|---|
| Star | Low (hub failure) | Moderate | Small office/home networks |
| Bus | None (backbone) | Low | Temporary setups, small networks |
| Ring | Moderate (token) | Moderate | Limited to legacy systems |
| Mesh | High | High | Large, secure, and reliable WANs |
| Hybrid | Depends on mix | High | Scalable enterprise networks |
MCQ
Q1. In which network topology is all the data traffic managed by a central device, such as a switch or a hub?
a) Bus Topology
b) Ring Topology
c) Star Topology
d) Mesh Topology
e) Tree Topology
Answer: c) Star Topology
Explanation: In a Star topology, all nodes (computers, printers, etc.) are connected to a single central device. All communication between nodes must pass through this central hub or switch.
Q2. Which of the following topologies has the highest reliability and redundancy?
a) Star Topology
b) Ring Topology
c) Bus Topology
d) Mesh Topology
e) Hybrid Topology
Answer: d) Mesh Topology
Explanation: In a full Mesh topology, every node is connected to every other node. This provides multiple paths for data to travel, so if one path fails, the data can be rerouted through another, making it highly reliable.
Q3. A company has 5 computers to be connected in a full mesh topology. How many cables are required to connect them?
a) 5
b) 20
c) 15
d) 10
e) 25
Answer: d) 10
Explanation: The formula to calculate the number of cables required for ‘n’ nodes in a full mesh topology is n(n−1)/2.
For n=5, the calculation is 5(5−1)/2=5×4/2=10.
Q4. A network topology that uses a single backbone cable to which all the devices are connected is known as _____.
a) Star
b) Ring
c) Bus
d) Tree
e) Mesh
Answer: c) Bus
Explanation: The Bus topology uses a common backbone or a single communication channel. A failure in this main cable can bring down the entire network.
Q5. The ‘Token Passing’ mechanism for channel access is a feature of which topology?
a) Star Topology
b) Bus Topology
c) Tree Topology
d) Ring Topology
e) Mesh Topology
Answer: d) Ring Topology
Explanation: In a Ring topology, a small data frame called a “token” is passed from one station to the next in a circular fashion. A station can only transmit data when it possesses the token.
Q6. Which topology is a combination of two or more different topologies to form a larger, more complex network?
a) Tree Topology
b) Hybrid Topology
c) Star Topology
d) Complex Topology
e) Mesh Topology
Answer: b) Hybrid Topology
Explanation: A Hybrid topology integrates two or more basic network topologies. For example, connecting a star network and a bus network creates a hybrid topology.
Q7. What is the primary disadvantage of a Ring topology?
a) It is very expensive to implement.
b) Adding or removing a node is very complex.
c) The failure of a single node can bring down the entire network.
d) It requires a central hub to function.
e) Data transmission is very slow.
Answer: c) The failure of a single node can bring down the entire network.
Explanation: Since data travels sequentially from one node to the next, a break in the ring (due to a failed node or cable) can halt all communication.
Q8. A hierarchical topology where star networks are connected to a linear bus backbone is known as a ______.
a) Ring Topology
b) Mesh Topology
c) Hybrid Topology
d) Tree Topology
e) Star-Bus Topology
Answer: d) Tree Topology
Explanation: The Tree topology has a root node, and all other nodes are linked to it forming a hierarchy. It is also described as a collection of star networks connected via a bus backbone.
Q9. Which of the following is considered a major drawback of the Star topology?
a) It is difficult to troubleshoot.
b) If the central hub or switch fails, the entire network becomes inoperable.
c) Network expansion is very difficult.
d) It is the most expensive topology.
e) Data collision rates are very high.
Answer: b) If the central hub or switch fails, the entire network becomes inoperable.
Explanation: The central device in a Star topology represents a single point of failure. Its failure affects all connected nodes.
Q10. In a Bus topology, what is the purpose of a ‘Terminator’ at each end of the main cable?
a) To connect the bus to the next network segment
b) To boost the signal strength
c) To absorb signals at the end of the line and prevent them from reflecting back
d) To assign an IP address to the end device
e) To filter network traffic
Answer: c) To absorb signals at the end of the line and prevent them from reflecting back