Mani Raj Paul - Study - what is Networking?

Networking

A network can be defined as a group of computers and other devices connected in some ways so as to be able to exchange data.
-Each of the devices on the network can be thought of as a node; each
node has a unique address.
-Addresses are numeric quantities that are easy for computers to work
with, but not for humans to remember.
Example: 204.160.241.98
-Some networks also provide names that humans can more easily remember than numbers.
Example: www.javasoft.com, corresponding to the above numeric address

Addressing

Internet address

Consists of 4 bytes separated by periods
Example: 136.102.233.49
-The R first bytes (R= 1,2,3) correspond to the network address;
-The remaining H bytes (H = 3,2,1) are used for the host machine.
-InterNIC Register: organization in charge of the allocation of the
address ranges corresponding to networks.
-Criteria considered:
→ Geographical area (country)
→ Organization, enterprise
→ Department
→ Host

Ports

-An IP address identifies a host machine on the Internet.
-An IP port will identify a specific application running on an Internet host
machine. 
-A port is identified by a number, the port number. 
-The number of ports is not functionally limited, in contrast to serial communications where only 4 ports are allowed.
-There are some port numbers which are dedicated for specific applications.

Protocols

-Define the rules that govern the communications between two computers connected to the network. 
-Roles: addressing and routing of messages, error detection and recovery, sequence and flow controls etc. 
-A protocol specification consists of the syntax, which defines the kinds
and formats of the messages exchanged, and the semantic, which specifies the action taken by each entity when specific events occur.
Example: HTTP protocol for communication between web browsers
and servers.





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