NETWORK ARCHITECTURE
The network architecture refers to how computers are organized and how tasks are allocated among these computers. It is mainly categorized into two major types :
PEER-TO-PEER NETWORK
A network of two or more computers that uses the same type of programs to communicate and share data is called a Peer-to-Peer network. Each computer or peer is considered equal in terms of responsibilities, and each acts as a server to others in the network. Peer-to-Peer networks work best in a small environment. These networks are designed primarily for small to medium local area networks. One should not use peer-to-peer network if more than 10 computers are to be connected together.
CLIENT/SERVER NETWORK
A network in which one or more computers are designated as server(s), and the other computers on the network, called clients, can request services from the server, is known as Client/Server Network.
SERVER
A server, sometimes called the host computer, controls access to the hardware and software on the network and provides a centralized storage area for programs, data, and information. When a user connects to the server, then applications, files, printers, etc. become available.
Some servers perform a specific task and are called dedicated servers.
For example, a file server stores and manages files.
A print server manages printers and documents being printed.
A network server manages network traffic.
A web server is a computer that delivers requested web pages
to your computer.
A database server stores and provides access to a database.
CLIENT
A Client is a computer system that relies on a server for all the resources. For example, a server might store a network version of word processing program. Every client on the network can access the word processing program on the server.
NETWORK TOPLOGY
In networking, the term topology refers to the layout structure of connected computers and devices on a network. A network topology has two levels, i.e., physical and logical.
The physical level refers to the parts of a network that physically exist, such as computers, cables and connectors. This level specifies where the computers on a network are located and how all the parts of the network are connected. Cables are the most popular transmission media to transfer information on a network.
The logical level refers to the path that the information takes to reach its destination on a network. The logical level of a network depends on many factors, such as the applications used and the volume of information transferred over the network. Computers share information by exchanging electrical signals. Signals are sent via the transmission medium that connects the computers.
Bus, Star and Ring are the three main types of network topologies.
BUS TOPOLOGY
In this kind of topology, all the computers and their devices are connected to one single cable called the Bus. This Bus network is also called linear network. It transmits data, instructions and information in both directions.
Only one computer can communicate at a time in bus topology. A device, wanting to communicate with another device on the network, sends a broadcast message onto the wire that all other devices can see, but only the intended recipient accepts and processes the message.
In this topology, computer system can be easily added or removed from the network. The failure of single node does not affect the performance of the remaining network.
STAR TOPOLOGY
In this kind of topology, connector called a hub is placed at the centre to which all the other nodes are connected. All the information that is transferred from one computer to another on the network, passes via the hub. Star network is one of the most common computer network topologies, because, it is easy to add or remove nodes. A failure in any star network cable will only take down network access of one computer and not the entire network. When the hub fails, then the network also fails.
RING TOPOLOGY
In ring topology, nodes are connected in a circular chain in which each node is connected to the next one and the last node is connected to the first one. Every device has exactly two neighbours for communication purpose. All messages travel through a ring in the same direction (either "clockwise" or "counter clockwise"). In this, if one node fails, the whole network goes off. Computers are usually located close together. A ring network is easy to set up because the computers are attached to a single ring of cable and no central connector, such as hub, is required. There is no beginning or end in a ring network.
PROTOCOL
A protocol is a set of rules that outlines characteristics of how two devices communicate over the network. There are different protocols for different operations on the Internet.
HTTP Hypertext Transfer Protocol): ( This is a set of rules that defines how pages transfer on the Internet and what actions web servers and browsers should take in response to various commands. Many web addresses begin with http:// as the protocol.
FTP (File Transfer Protocol): This is a set of rules that allows file uploading to and downloading from other computers on the Internet. Uploading is the process of transferring files from your computer to a server on the Internet. Downloading is the process of transferring files from a server on the Internet to your computer. Web page developers often use FTP to upload their webpages to a web server.
TCP/IP (Transmission Control Protocol/Internet Protocol): This is a network protocol that defines how the information or messages are routed from one end of a network to the other, ensuring the data arrives correctly. It has been used as network standard for Internet communications.
POP3 (Post Office Protocol version 3): This is an email protocol that stores email messages on a mail server and allows the user to view, access and manipulate the message after downloading or storing it on their computer. Once the messages are downloaded onto your computer, they are deleted from the mail server. This means that after the email is downloaded, it can only be accessed using the same computer. If you try to access your email from a different device, the messages that have been previously downloaded will not be available to you.
IMAP (Internet Message Access Protocol): This is also an email protocol that stores email messages on a mail server and allows the user to view, access and manipulate the messages on the mail server from their computer. When you read an email message using IMAP, you are not actually downloading or storing it on your computer; instead, you are reading it on the mail server from your computer. As a result, if you try to access your email from a different device, the same messages will be available to you.
SMTP (Simple Mail Transfer Protocol): This is an email protocol for sending email messages across the Internet. SMTP was originally developed in the early 1980s and remains one of the most popular protocols in use worldwide. Most email software programs use SMTP for sending mails and use either the POP3 or IMAP protocol for receiving mails.
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