collision domain and broadcast domain

[abhilash_cpy]

please tell me the clear difference between broadcast domain and collision domain

[ciscodaze]

Remember this: Routers break up broadcast domains - Switches break up collision domains.

Everything on one subnet is a broadcast domain. Why? Because broadcasts do not cross your router - (meaning they are not forwarded by your router) and are therefore confined to the "broadcast domain". This is also true of VLANs by the way. Each VLAN is a broadcast domain, because each VLAN is a subnet.

Remember this also: a VLAN = a SUBNET = a BROADCAST DOMAIN

Collision domains are broken up by switches because each ethernet port is point to point connection, therefore no collisions can take place on that segment, and it is a collision domain.

If you throw a hub into the mix somewhere off of one of the ethernet ports, you are no longer point to point, as a dumb hub just copies frames out every hub port. This means everthing connected to the hub is part of one big collision domain because collisions can now happen. And that portion of you LAN will also have to run at half-duplex because of CSMA/CD.