Do the smallest Lans have a backbone?

Answer 1

Can you define "Smallest LANs"?

First you need to determine which type of LAN you are referring to, if it is home network, it should be a WORKGROUP or a Peer-to-Peer Environment.

If you are referring to small Network Branch of an Existing Network, it is possibly connected to pre-defined backbone.

Since, A backbone network or network backbone is a part of computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas. Normally, the backbone's capacity is greater than the networks connected to it.

source: www.Wikipedia.org