Question

A broadcast network is one in which a transmission from any one attached station is received by all other attached stations over a shared medium. examples are a bustopology local area network, such as ethernet, and a wireless radio network. discuss the need or lack of need for a network layer (osi layer 3) in a broadcast network

Answer 1

Broadcast frames are layer 2 and not Layer 3, examples are DHCP/ARP/RARP etc.  request.  A Router will block all broadcast traffic unless configured to let the specific packet through via the IP Helper statement to direct to a remote DHCP server and back.
Obviously, a bus topology this is OLD technology they rarely exist anymore. Today, switches have taken over the dumb hubs or even vampire taps on a coax cable. However, a broadcast it still passed on to every port on the switch, unless configured not to do so. Anyway, I could go on and on.