What is the drawback of using a BUS topology?

Concept

A bus topology connects every node to a single shared backbone cable, which acts as one common broadcast medium. Because the medium is shared, only one device can transmit successfully at a time; access to the cable is governed by a media-access / collision-handling scheme, and the cable's total bandwidth is split among all active senders.

Applying it here

• Every computer taps into the same backbone, so all of them compete for the one channel.

• Adding more computers, or sending more traffic, increases contention for that single shared cable.

• More simultaneous attempts to transmit mean more collisions, which force retransmissions and add delay.

• The fixed cable bandwidth is now divided among more active nodes, so each node's effective throughput and response time get worse.

So the defining weakness is that throughput and responsiveness fall as the number of computers grows or as traffic rises — the network does not scale well under load.

Why the other choices fail

• "Only a pair of nodes can be connected" — false; a bus's whole purpose is to let many nodes share one cable, not just two.

• "There are no drawbacks" — false; the contention, collisions, and single-cable point of failure are exactly its well-known weaknesses.

• "Very slow data rates" — a bus is not inherently slow; under light load it performs fine. The problem is degradation as load and node count rise, not a low baseline rate.