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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.

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.

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.

The different types of network TOPOLOGY are given below:

Bus Topology:

• All the nodes are connected using the central link known as the bus.
• It is useful to connect a SMALLER number of devices.
• If the main cable gets damaged, it will damage the whole network.

Star Topology:

• All the nodes are connected to one single node known as the central node.
• It is more robust.
• If the central node fails the complete network is damaged.
• Easy to troubleshoot.
• Mainly used in home and office networks.

Ring Topology:

• Each node is connected to EXACTLY TWO nodes forming a ring structure
• If one of the nodes are damaged, it will damage the whole network
• It is used very rarely as it is expensive and hard to install and manage

Mesh Topology:

• Each node is connected to one or many nodes.
• It is robust as failure in one link only disconnects that node.
• It is rarely used and installation and MANAGEMENT are difficult.

Tree Topology:

• A combination of star and bus topology also know as an extended bus topology.
• All the smaller star networks are connected to a single bus.
• If the main bus fails, the whole network is damaged.

Hybrid:

• It is a combination of different topologies to form a new topology.
• It helps to ignore the drawback of a particular topology and helps to pick the strengths from other.

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.

Node: Any communicating device in a NETWORK is called a Node. 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.

Few types of VPN are:

• 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.

Below are few ADVANTAGES of using 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.

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:

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.

Below are few types of networks:

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: