4) how networks are structure and roles of the servers ICT-unit-1

Network Structures

Networks can be structured in various ways, depending on their size, function, and complexity. Here are common types of network structures:

1. Peer-to-Peer (P2P) Networks:

Structure: In a P2P network, all computers (nodes) are equal and directly connected to one another. There is no central authority or dedicated server. Each device (peer) acts as both a client and a server, sharing files, printers, or other resources with other peers.
Example: Small home networks where devices share files directly.

2. Client-Server Networks:

Structure: In a client-server network, there are dedicated **servers** that provide resources and services (like data, files, applications) to **clients** (computers or devices) that request these services. Servers handle resource management and centralize the control of data, while clients access these resources.
Example: Corporate networks where workstations connect to a central server for file storage, email, or databases.

3. LAN (Local Area Network):

Structure: A LAN connects devices within a small geographic area, like a building or office. LANs often have a client-server structure, but can also be peer-to-peer. Enables fast data transfer between local devices, allowing users to share resources such as printers, files, and internet access.
Example: An office network connecting multiple computers, printers, and routers.

4. WAN (Wide Area Network):

Structure: WANs connect multiple LANs over large geographic distances (such as cities or countries) using telecommunications links. Facilitates communication and data sharing between users in different locations.
Example: The Internet is a massive WAN connecting millions of devices worldwide.

5. Wireless Networks (WLAN):

Structure: WLANs use wireless technologies (like Wi-Fi) to connect devices in a local area, without requiring physical cables. Allows for mobility and flexible device connections without the need for wired infrastructure.
Example: A home Wi-Fi network where multiple devices connect to the same router.

Roles of Servers in a Network

Servers play a critical role in providing centralized services and managing network resources. Here are common types of servers and their functions:

1.File Server:

Stores and manages files so that users (clients) can access, upload, and modify shared documents. In an office, employees access documents stored on the file server, which manages storage, security, and backups.

2. Web Server:

Hosts websites and delivers web content (HTML pages, images, scripts) to users via the internet or intranet. A web server like Apache or Nginx hosts company websites, allowing users to browse them online.

3. Database Server:

Manages databases and handles data storage, queries, and updates. It processes requests from clients who need to retrieve or modify data. A MySQL server handling requests for data in an e-commerce platform, such as customer information or product details.

4. Application Server:

Runs and manages applications for users across the network. It handles the backend logic for specific applications (like payroll or ERP systems). A Tomcat application server running business software for an organization, allowing employees to interact with internal tools.

5. Email Server:

Manages the sending, receiving, and storing of emails for users within the network. A Microsoft Exchange or Gmail server processes incoming and outgoing mail for users in a business or educational setting.

6.DNS Server:

Translates domain names (like www.example.com) into IP addresses that computers can understand, enabling access to websites. When you type a website URL into your browser, a DNS server converts that URL into the correct IP address to reach the website.

7.Proxy Server:

Acts as an intermediary between clients and other servers, providing security, content filtering, and anonymity by masking the client’s identity. A proxy server used by a company to control employee internet usage and block access to certain websites.

8. Print Server:

Manages print jobs from multiple clients, allowing users to send print requests to shared printers within the network. An office print server that queues and handles print requests from different computers.

9. Backup Server :

Regularly backs up data from other computers or servers on the network to prevent data loss and ensure recovery in case of failure.