Which of the following statements are incorrect about the differences between routers and Layer 2...

The incorrect statements are A and C .

A router works at the network layer and is used to connect different networks. By default, a router separates broadcast domains , because broadcasts are not forwarded from one interface to another. At the same time, each router interface also represents an independent network segment, so routers effectively separate collision domains as well. Therefore, the statement that routers can isolate broadcast domains but not collision domains is incorrect.

A Layer 2 switch works at the data link layer. Each switch port forms a separate collision domain , which is why switches can isolate collision domains. However, by default, all ports in the same VLAN still belong to the same broadcast domain , so switches forward broadcast traffic out all relevant ports. That makes statement B correct and statement D correct.

Statement C is incorrect because routers generally do not forward broadcast packets . Preventing broadcast propagation between networks is one of the key differences between routers and switches. Therefore, the incorrect options are A and C .