What are the essential " networking functions " required to implement a network ?

Depends on what type of " network " you mean.

Social networking I can't help.

Networking 'puters, read: OSI Model, TCP/IP Stack, infinite other resources

Off the bat: some way to identify (name) servers and resolve their physical address from such an identity, a way to represent the input of a request and the output of a response, and some way to remember active processes asynchronously so when they complete their output can be directed to the right request.

Networking is a big topic though and not one that can really be summarized in a single comment.

Unless you really want to reinvent the wheel you probably want to research TCP/IP.

Probably proper addressing and routing. Without this I don't think we are talking about networks anymore. Clustering in the sense of establishing a backbone through the nodes also helps getting efficient. There are proper algorithms for selecting cluster heads and rotating them. If you are talking wireless have a look at how zigbee handles these things.

Have fun :)

@BigBoo typical network to facilitate new application .

This is first Homework given at our first day of Computer Networks course

@dufferz 😊😊👍

@devios1 yeah..I include them switching ,routing ,addressing 😊😊

Thank You very much !

@jerengie Thank You very much for you information..

and Welcome to Devrant 😍😉😊👍

@Alexiussachitha It all depends on what you mean still.

CSMA/CD
CSMA/CA
works differently in a networking sense.

But in an application sense it doesn't matter.
Tcp doesn't care which one you use.

Do you need a protocol? Yes, probably some sort. But you don't need to use ip if you don't want to. But it does make everything a whole lot convenient when routing packages.

You can memorize what an Ethernet package look like.
What an IP package look like.
What a TCP package look like.
UDP.
HTTP.

Are Bluetooth included?

2.4 GHz wireless devices?

Your question is extremely open.