Networks, What do you mean by that? - Pentestmag

Networks, What do you mean by that?


Have you ever heard of words like Generation X, Generation Y, Lost generation, etc.? These are the words that are generally used by people to identify the period that they were born. So, according to this terminology, a large percentage of this world is called iGen or Generation Z (generally used for people born between 1995-2012). But since we live in this glorious age of computers, where we spend most of our time with the internet as our dear companion, it would be more sensible to call this the Cyber Generation, but that’s just my opinion. So, in this cyber age if we just take a moment, and think about the basic and important things that help us in using our dear friend, we will always come across a term called Network.

So, I think most people have at least wondered about questions like what is the Internet, how does it work, how can we access the internet, etc. Well, if you’ve had these questions at some point in your life, then I think I can at least satisfy your curiosity in a small way.

So, what is a network? The answer is simple. A network is defined as a group of two or more computer systems linked together. Well, we answered the first question and it was not that hard, right? After learning this, a person might think about why we need to learn about networks and what their uses are. So, let’s provide the answer for that first.

Uses Of Networks

  • For resource sharing, as the same device in a network can be accessed by a different computer that is connected to the same network like the printer, fax, scanner, etc.
  • For information sharing: The exchange of data between various organizations, people, and technologies. Different information and data can be shared like files, videos, etc.
  • For communication like chatting, video calling, emails, etc.
  • In E-commerce where users can pay bills, transfer cash, buying goods, etc., using the computer.

The next question that comes to mind when we know what a network is and its uses, are if there are different types of networks, if yes, then what those are. The answer is yes, there are five different types of networks. Let’s discuss them in detail.

Types of Networks

  • Local Area Networks (LAN): This term is used to describe those networks where the computers are geographically close together that is, in the same building. If you’re a gamer, then you probably would have heard this word, as it was a very useful component if you had to challenge your friends, cousins, buddies, bros, etc., in the multiplayer mode when they come to visit you to earn some bragging rights.
  • Wide Area Networks (WAN): This term is used to describe those networks where the computers are farther apart (the computers are located in a different city, country or continent) and are connected by telephone lines or radio waves. If you’re a gamer, then you probably would have heard this word, as it was used to challenge the online players from other cities, countries or countries in the multiplayer mode to improve your game.
  • Campus Area Networks (CAN): This term is used to describe those networks where the computers are located within a limited geographic area, such as a campus or military base. It is basically a set of interconnected LANs. The end users in a campus network may be dispersed more widely in a geographical sense than in a single LAN, but they are usually not as scattered as they would be in a WAN.
  • Metropolitan Area Networks (MAN): This term is used to describe those networks where the computers are the interconnection of networks in a city into a single larger network, which may then also offer efficient connection to a wide area network. It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network with the difference that a MAN operates within a city, unlike a CAN, which operates inside a campus.
  • Home Area Networks (HAN): This term is used to describe those networks where the computers are contained within a user's home that connects a person's digital devices.

Before going any further, I would like to explain some concepts that will be used in the feature.

  • Topology: The layout pattern of the interconnections between computers in a network is called network topology. A person can think of topology as the virtual shape or structure of the network. Network topology is also referred to as 'Network architecture.'
  • Protocol: It is defined as a common set of rules and signals that computers on the network use to communicate. One of the most popular protocols for LANs is called Ethernet. Another popular LAN protocol for PCs is the IBM token-ring network.
  • Servers: These are the computers and devices that allocate resources for a network.

Since we have a basic understanding of what a topology is, I think now is the perfect time to explain about the types of networking topologies.

Types of Network Topologies

  • Point-to-Point topology: It is the simplest of all the network topologies. The network consists of a direct link between two computers. This is faster and more reliable than other types of connections since there is a direct connection. The disadvantage is that it can only be used for small areas where computers are in close proximity.
  • Bus topology: It uses one main cable to which all nodes are directly connected. The main cable acts as a backbone for the network. One of the computers in the network typically acts as the computer server. The advantage of bus topology is that it is easy to connect a computer or peripheral device. The disadvantages is that if the main cable breaks, the entire network goes down.
  • Star topology: It is very popular because the startup costs are low. It is also easy to add new nodes to the network. If the central hub fails, however, the entire network goes down. It also requires more cable than bus topology and is, therefore, more expensive.
  • Ring topology: Here, the computers in the network are connected in a circular fashion, and the data travels in one direction. Each computer is directly connected to the next computer, forming a single pathway for signals through the network. This type of network is easy to install and manage. On the downside, adding computers to this type of network is more cumbersome, and if one single computer fails, the entire network goes down.
  • Mesh topology: Here, every node has a direct point-to-point connection to every other node. Because all connections are direct, the network can handle very high-volume traffic. This type of topology requires a lot of cables and is, therefore, expensive.
  • Tree topology: It has a root node and all other nodes are connected to it forming a hierarchy. It is also called hierarchical topology. It should at least have three levels to the hierarchy. Its advantage is that it is an extension of bus and star topologies and expansion of nodes is possible and easy. But it is heavily cabled and costly.
  • Hybrid topology: It is a mixture of two or more topologies. For example, if in an office in one department ring topology is used and in another star topology is used, connecting these topologies will result in Hybrid Topology (ring topology and star topology).

Whether it’s wired or wireless, most data communication today happens by way of packets of information travelling over one or more networks. Before these networks can work together, though, they must use a common protocol, or a set of rules for transmitting and receiving these packets of data. Many protocols have been developed. One of the most widely used is the Transmission Control Protocol/Internet Protocol (TCP/IP). Also, a generic protocol model used in describing network communications known as the Open System Interconnection (OSI) model is useful for comparing and contrasting different protocols. Now, let’s discuss these two protocols in detail.

TCP/IP Layer

TCP/IP means Transmission Control Protocol and Internet Protocol. It is the network model used in the current Internet architecture as well. Protocols are sets of rules that govern every possible communication over a network. These protocols describe the movement of data between the source and destination or the internet. These protocols offer simple naming and addressing schemes.

  • Layer 1 (Network Interface Layer): It is also called the Network Access layer and is responsible for placing TCP/IP packets on the network medium and receiving TCP/IP packets off the network medium. TCP/IP was designed to be independent of the network access method, frame format, and medium. In this way, TCP/IP can be used to connect differing network types. Independence from any specific network technology gives TCP/IP the ability to be adapted to new technologies such as Asynchronous Transfer Mode (ATM).
  • Layer 2 (Internet Layer): The Internet layer is responsible for addressing, packaging, and routing functions. The core protocols of the Internet layer are IP, ARP, ICMP, and IGMP.
  • Layer 3 (Transport Layer): It is also known as the Host-to-Host Transport layer and is responsible for providing the Application layer with session and datagram communication services. The core protocols of the Transport layer are Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).
  • Layer 4 (Application Layer): The Application layer provides applications the ability to access the services of the other layers and defines the protocols that applications use to exchange data. There are many Application layer protocols and new protocols are always being developed.

OSI Layer

The OSI model is just that, a model. Its use is not mandated for networking, yet most protocols and systems adhere to it quite closely. It is mainly useful for discussing, describing, and understanding individual network functions. Not all layers are used in some simpler applications. While layers 1, 2, and 3 are mandatory for any data transmission, the application may use some unique interface layer to the application instead of the usual upper layers of the model. It comprises of the following seven layers:

  • Layer 1 (Physical Layer): This layer is responsible for ultimate transmission of digital data bits from the physical layer of the sending (source) device over network communications media to the Physical layer of the receiving (destination) device.
  • Layer 2 (Data Link Layer): When data from the Physical layer is obtained, then the Data Link layer checks for physical transmission errors and packages bits into data frames. It also manages physical addressing schemes such as MAC addresses for Ethernet networks, controlling access of any various network devices to the physical medium.
  • Layer 3 (Network Layer): When data arrives at the Network layer, the source and destination addresses contained inside each frame are examined to determine if the data has reached its final destination. If the data has reached the final destination, this layer formats the data into packets delivered up to the Transport layer. Otherwise, the Network layer updates the destination address and pushes the frame back down to the lower layers.
  • Layer 4 (Transport Layer): The Transport Layer delivers data across network connections. TCP is the most common example of this protocol. Different transport protocols may support a range of optional capabilities including error recovery, flow control, and support for re-transmission.
  • Layer 5 (Session Layer): The Session Layer manages the sequence and flow of events that initiate and tear down network connections. This layer is built to support multiple types of connections that can be created dynamically and run over individual networks.
  • Layer 6 (Presentation Layer): The Presentation layer is the simplest in function of any piece of the OSI model. It handles syntax processing of message data such as format conversions and encryption / decryption needed to support the Application layer above it.
  • Layer 7 (Application Layer): The Application layer supplies network services to end-user applications. Network services are typically protocols that work with user's data. For example, in a Web browser application, the Application layer protocol HTTP packages the data needed to send and receive Web page content. It provides data to (and obtains data from) the Presentation layer.


So, this article satisfies a person’s curiosity about the basics of network, its uses, types, topologies and the two important transport protocols that are used for communication of data. This knowledge is just the basic of the concept of networking and tells us about the basic know how of this subject.


[1] 2016· CISCO CCNA/CCENT ICND1 100-101 Official Cert Guide, Third Edition, by Odom, Wendell

Author: Debashish Pandey

I am a student currently pursuing Bachelor's of Technology in Computer Science Engineering with specialization in IT Security and Cyber Forensics from University of Petroleum and Energy Studies, Dehradun. I have a keen interest in Network Security, Digital Forensics and Information Security. My aim is to succeed in an environment of growth and excellence and spend my life doing something which provides me satisfaction, self development and helps me achieve personal as well as organizational goals.

December 28, 2017
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