Collision domain and broadcast domain question

[hiyalim]

How many subnets, Collision domain and broadcast domain in the following network (see attached)?

[Karsten Iwen]

It's a homework? Just tell us what you think and why. If it is not correct you will get some hints to help you learning.

[Georg Pauwen]

Hello,

you have three at the very least. The unknown is the switch on the left side, and whether PC0 and PC1 are in the same or different Vlans, and if trunking and subinterfaces are being used on the router. So it is either three or four...

[Joseph W. Doherty]

Insufficient information to say.

On each router port, multiple networks could be defined.

As noted by Georg, the switch might be hosting different VLANs. Further, as we don't know whether the switch links are operating in half or full duplex mode, so we cannot answer the question on its collision domains.

We can say, the hub's link would all be in the same collision domain and broadcast domain. We can also say, the WAN link would be in its own broadcast domain, assuming the WAN media supports broadcasts.

[hiyalim]

Thanks for your answers.

So a switch has a single broadcast domain and its collision domains depend on the number of its ports that has devices connected to it. Correct?

A router has broadcast domains & collision domains each as many as devices connected to its interfaces. Correct?

The hub has one collision domain and broadcast domain on all ports. Correct?

So I count 5 collision domains and 3 broadcast domains.

[Joseph W. Doherty]

"The hub has one collision domain and broadcast domain on all ports. Correct?"

Yes.

"So a switch has a single broadcast domain and its collision domains depend on the number of its ports that has devices connected to it. Correct?"

No.

If a switch port is operating in full duplex, there is no collision domain for that port. If it's operating in half duplex, there's a collision domain for the port.

Broadcast domains are per VLAN.

"A router has broadcast domains & collision domains each as many as devices connected to its interfaces. Correct?"

No.

A router port might be in full duplex mode, and if so, there's no collision domain for that port.

If the router is routing, broadcast domains would be per port, but many routers can bridge too, and if they are, then the broadcast domain can extend to multiple router ports.