# Computer Networking **What is the network?** A network is usually an informally interconnected group or association of different entities like a person, computers, radio stations, etc. For example, Dominos has a network of 1232 branches across India. As the name suggests the computer network is a system of peripherals or computers interconnected with each other and has a standard communication channel established between them to exchange different types of information and data. **How are Network types classified?** Network types can be classified and divided based on the area of distribution of the network. The below diagram would help to understand the same: ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1692374962809/3e923a65-efab-4d20-9980-6aa0c734506b.png align="center") **Explain different types of networks. ?** PAN (Personal Area Network): Let devices connect and communicate over the range of a person. E.g. connecting Bluetooth devices. LAN (Local Area Network): It is a privately owned network that operates within and nearby a single building like a home, office, or factory. MAN (Metropolitan Area Network): It connects and covers the whole city. E.g. TV Cable connection over the city WAN (Wide Area Network): It spans a large geographical area, often a country or continent. The Internet is the largest WAN GAN (Global Area Network): It is also known as the Internet which connects the globe using satellites. The Internet is also called the Network of WANs. **Explain LAN (Local Area Network)?** LANs are widely used to connect computers/laptops and consumer electronics which enables them to share resources (e.g., printers, fax machines) and exchange information. When LANs are used by companies or organizations, they are called **enterprise networks**. There are two different types of LAN networks i.e. wireless LAN (no wires involved achieved using Wi-Fi) and wired LAN (achieved using LAN cable). Wireless LANs are very popular these days for places where installing wire is difficult. The below diagrams explain both wireless and wired LAN ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1692382195371/4c912c95-315e-4e08-ba1d-63473e43b294.png align="center") **LAN (Local Area Network)** **About VPN (Virtual Private Network)** VPN or the Virtual Private Network is a private WAN (Wide Area Network) built on the internet. It allows the creation of a secured tunnel (protected network) between different networks using the internet (public network). By using the VPN, a client can connect to the organization’s network remotely. The below diagram shows an organizational WAN network over Australia created using VPN: ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1692382418947/3c46789b-5d4a-4cae-ada5-f1fccbe5078d.png align="center") Advantages of using a VPN? Below are a few advantages of using a VPN: VPN is used to connect offices in different geographical locations remotely and is cheaper when compared to WAN connections. VPN is used for secure transactions and confidential data transfer between multiple offices located in different geographical locations. VPN keeps an organization’s information secured against any potential threats or intrusions by using virtualization. VPN encrypts the internet traffic and disguises the online identity Different types of VPN?  Access VPN: Access VPN is used to provide connectivity to remote mobile users and telecommuters. It serves as an alternative to dial-up connections or ISDN (Integrated Services Digital Network) connections. It is a low-cost solution and provides a wide range of connectivity. Site-to-Site VPN: A Site-to-Site or Router-to-Router VPN is commonly used in large companies having branches in different locations to connect the network of one office to another in different locations. There are 2 sub-categories as mentioned below: Intranet VPN: Intranet VPN is useful for connecting remote offices in different geographical locations using shared infrastructure (internet connectivity and servers) with the same accessibility policies as a private WAN (wide area network). Extranet VPN: Extranet VPN uses shared infrastructure over an intranet, suppliers, customers, partners, and other entities and connects them using dedicated connections  **Nodes and Links?** Node: Any communicating device in a network is called a Node. The node is the point of intersection in a network. It can send/receive data and information within a network. Examples of the node can be computers, laptops, printers, servers, modems, etc. Link: A link or edge refers to the connectivity between two nodes in the network. It includes the type of connectivity (wired or wireless) between the nodes and protocols used for one node to be able to communicate with the other. ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1692382843112/0aca9fa2-4e97-46e4-989c-c3e144fcce17.png align="center") **Network Topology:** Network topology is a physical layout of the network, connecting the different nodes using the links. It depicts the connectivity between the computers, devices, cables, etc. **What is an IPv4 address? What are the different classes of IPv4?** An IP address is a 32-bit dynamic address of a node in the network. An IPv4 address has 4 octets of 8-bit each with each number with a value up to 255. IPv4 classes are differentiated based on the number of hosts it supports on the network. There are five types of IPv4 classes and are based on the first octet of IP addresses which are classified as Class A, B, C, D, or E. ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1692383167076/223ff3ef-cd6f-46f8-ab0a-b9b4a36f9290.png align="center") **What are Private and Special IP addresses?** Private Address: For each class, there are specific IPs that are reserved specifically for private use only. This IP address cannot be used for devices on the Internet as they are non-routable.  ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1692383362758/c1b603d8-0d66-4960-a3c0-0285f86b6d47.png align="center") Special Address: IP Range from 127.0.0.1 to 127.255.255.255 are network testing addresses also known as loopback addresses are the special IP address.