IT: Basic Fundamental Concepts of The Computer Network

The benefits of basic different concepts about computer networking are right around you.

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Hello, Dear Readers and followers, welcome back to my new story, I hope all’s well. Today I planned to talk about some basic fundamental concepts of the computer network.

Computer Network is basically connecting different computers or nodes together so that you can share resources or communicate with each other.


A network is a collection of computers, servers, mainframes, network devices, peripherals, or other devices connected to allow data sharing. An example of a network is the Internet, which connects millions of people all over the world. To the right is an example image of a home network with multiple computers and other network devices all connected.

Computer Networks are built using a collection of hardware (such as routers, switches, hubs, and so forth) and networking software (such as operating systems, firewalls, or corporate applications).

One can also describe the concept of computer networking by its communicating protocols, the physical arrangement of its networking elements, how it manages network traffic, and its functioning.

Computer networks are globally used by businesses, the entertainment industry, and education in the research field for communication and transferring their data from source to destination node.

All the other technologies, including the internet, Google search, instant messaging apps, online video streaming, social media, email, cloud kitchen, cloud data storage, etc., all exist because of computer networks.

Wires Cables & Wifi

A Computer Network is defined as a set of two or more computers that are linked together. either via wired cables or wireless networks i.e., WiFi?with the purpose of communicating, exchanging, sharing, or distributing data, files, and resources.

Wires Cables

Cabling is the set of wires made of either copper or glass that is used to connect computers and other network components to enable them to communicate, thus forming a network of computers. The main types of network cables are coax, fiber optics, and shielded and unshielded twisted pair.

In other words, Network Cabling is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. In some cases, a network will utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network’s topology, protocol, and size. Understanding the characteristics of different types of cable and how they relate to other aspects of a network is necessary for the development of a successful network.

Laying cables is the foundation for both creating local area networks (LANs) and connecting LANs into wide area networks (WANs). Network administrators are usually involved only in the planning and laying of LAN cabling since WAN cabling is the responsibility of telecommunications carriers.

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Wi-Fi is a wireless technology used to connect computers, tablets, smartphones and other devices to the internet. Wi-Fi is the radio signal sent from a wireless router to a nearby device, which translates the signal into data you can see and use. The device transmits a radio signal back to the router, which connects to the internet by wire or cable.

A Wi-Fi network is simply an internet connection that’s shared with multiple devices in a home or business via a wireless router. The router is connected directly to your internet modem and acts as a hub to broadcast the internet signal to all your Wi-Fi enabled devices. This gives you flexibility to stay connected to the internet as long as you’re within your network coverage area.

Wi-Fi uses radio waves to transmit data from your wireless router to your Wi-Fi enabled devices like your TV, smartphone, tablet and computer. Because they communicate with each other over airwaves, your devices and personal information can become vulnerable to hackers, cyber-attacks and other threats. This is especially true when you connect to a public Wi-Fi network at places like a coffee shop or airport. When possible, it’s best to connect to a wireless network that is password-protected or a personal hotspot.

Wi-Fi Standards

Wireless standards are a set of services and protocols that dictate how your Wi-Fi network (and other data transmission networks) acts.

The most common wireless standards you will encounter are the IEEE 802.11 Wireless LAN (WLAN) & Mesh. The IEEE updates the 802.11 Wi-Fi standard every few years. At the time of writing, the most commonly used Wi-Fi standard is 802.11ac, while the next generation Wi-Fi standard, 802.11ax (also known as Wi-Fi 6 and Wi-Fi6E — but more on this in a moment!), is rolling out, albeit slower than most experts thought.

  • IEEE 802.11: The original! This now-defunct standard was created in 1997 and supported a blazing fast maximum connection speed of 54 megabits per second (Mbps). Devices using this haven’t been made for over a decade and won’t work with today’s equipment.
  • IEEE 802.11a: Created in 1999, this version of Wi-Fi works on the 5GHz band. This was done with the hope of encountering less interference since many devices (like most wireless phones) also use the 2.4GHz band. 802.11a is fairly quick, too, with maximum data rates topping out at 54Mbps. However, the 5GHz frequency has more difficulty with objects in the signal’s path, so the range is often poor.
  • IEEE 802.11b: Also created in 1999, this standard uses the more typical 2.4GHz band and can achieve a maximum speed of 11Mbps. 802.11b was the standard that kick-started Wi-Fi’s popularity.
  • IEEE 802.11g: Designed in 2003, the 802.11g standard upped the maximum data rate to 54Mbps while retaining use of the reliable 2.4GHz band. This resulted in the widespread adoption of the standard.
  • IEEE 802.11n: Introduced in 2009, this version had slow initial adoption. 802.11n operates on both 2.4GHz and 5GHz, as well as supporting multi-channel usage. Each channel offers a maximum data rate of 150Mbps, which means the standard’s maximum data rate is 600Mbps.
  • IEEE 802.11ac: The ac standard is what you will find most wireless devices using at the time of writing. Initially released in 2014, ac drastically increases the data throughput for Wi-Fi devices up to a maximum of 1,300 megabits per second. Furthermore, ac adds MU-MIMO support, additional Wi-Fi broadcast channels for the 5GHz band, and support for more antennas on a single router.
  • IEEE 802.11ax: Next up for your router and your wireless devices is the ax standard. As 802.11ax completes its rollout, you will have access to theoretical network throughput of 10Gbps — around a 30–40 percent improvement over the ac standard. Furthermore, wireless ax will increase network capacity by adding broadcast subchannels, upgrading MU-MIMO, and allowing more simultaneous data streams.
  • IEEE 802.11be: Although the specifications for 802.11be are yet to be finalized, its highly likely that this will become the successor to 802.11ax. As per the IEEE Xplore paper, 802.11be will deliver “doubled bandwidth and the increased number of spatial streams, which together provide data rates as high as 40 Gbps.”

Wi-Fi 6

Wi-Fi 6 is the Wi-Fi Alliance’s wireless standard naming system. The Wi-Fi Alliance argues that the 802.11 terminology is confusing for consumers. They are right; updating one or two letters doesn’t give users much information to work with.

The Wi-Fi Alliance naming system runs concurrently with the IEEE 802.11 convention.

Wi-Fi 6E:

Wi-Fi 6 became a widespread Wi-Fi standard throughout 2020. But by the end of 2020, another “new” standard was beginning to pick up the pace.

Wi-Fi 6E is an extension of Wi-Fi 6. The update allows your Wi-Fi connection to broadcast over a new 6GHz band.

Previously, all Wi-Fi connections were restricted to two bands, 2.4GHz and 5GHz. Those two frequency bands are busy, with each band broken down into smaller channels. For instance, if you live in an apartment building, you may have many Wi-Fi routers attempting to broadcast on the same frequency, using the same channel.

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Common Types of Networks

Though one can also define computer networks based on their geographic location, a LAN (local area network) connects computers in a definite physical dimension, such as a home or within an office. In contrast, a MAN (Metropolitan area network) connects computers ranging between multiple buildings in a city. The Internet is the most significant example of WAN (Wide Area Network), connecting billions of networking devices across the world.

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Network Topology

The word “topology” comes from topos, which is Greek for «place». In computer networking, TOPOLOGY is the physical layout of computers, cables, switches, routers, and other components of a network. This term can also refer to the underlying network architecture, such as Ethernet or Token Ring.

When you design a network, your choice of topology will be determined by the size, architecture, cost, and management of the network. Basic network topologies include the following:

  1. Bus Topology
  2. Ring Topology
  3. Star Topology
  4. Mesh Topology
  5. Tree Topology
  6. Hybrid Topology

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The Network Layer

Network-to-network connections are what make the Internet possible. The “network layer” is the part of the Internet communications process where these connections occur, by sending packets of data back and forth between different networks. In the 7-layer OSI model (see below), the network layer is layer 3. The Internet Protocol (IP) is one of the main protocols used at this layer, along with several other protocols for routing, testing, and encryption.

Suppose Bob and Alice are connected to the same local area network (LAN), and Bob wants to send Alice a message. Because Bob is on the same network as Alice, he could send it directly to her computer across the network. However, if Alice is instead on a different LAN several miles away, Bob’s message will have to be addressed and sent to Alice’s network before it can reach her computer, which is a network layer process.

What happens at the network layer?

Anything that has to do with inter-network connections takes place at the network layer. This includes setting up the routes for data packets to take, checking to see if a server in another network is up and running, and addressing and receiving IP packets from other networks. This last process is perhaps the most important, as the vast majority of Internet traffic is sent over IP.

The Internet: IP Addresses & DNS

An IP address or Internet Protocol is a unique number that represents the address where you live on the Internet. Every device that is connected to the network has a string of numbers or IP addresses, unlike house addresses.

You won’t find two devices connected to a network with an identical IP address. When your computer sends data to another different, the sent data contains a ‘header’ that further contains the devices’ IP address, i.e., the source computer and the destination device.

Internet Protocol (IP)

The Internet Protocol (IP) is a protocol, or set of rules, for routing and addressing packets of data so that they can travel across networks and arrive at the correct destination. Data traversing the Internet is divided into smaller pieces, called packets. IP information is attached to each packet, and this information helps routers to send packets to the right place. Every device or domain that connects to the Internet is assigned an IP address, and as packets are directed to the IP address attached to them, data arrives where it is needed.

Once the packets arrive at their destination, they are handled differently depending on which transport protocol is used in combination with IP. The most common transport protocols are TCP and UDP.

The Transmission Control Protocol (TCP)

The Transmission Control Protocol (TCP) is a transport protocol, meaning it dictates the way data is sent and received. A TCP header is included in the data portion of each packet that uses TCP/IP. Before transmitting data, TCP opens a connection with the recipient. TCP ensures that all packets arrive in order once transmission begins. Via TCP, the recipient will acknowledge receiving each packet that arrives. Missing packets will be sent again if the receipt is not acknowledged.

TCP is designed for reliability, not speed. Because TCP has to make sure all packets arrive in order, loading data via TCP/IP can take longer if some packets are missing.

TCP and IP were originally designed to be used together, and these are often referred to as the TCP/IP suite. However, other transport protocols can be used with IP.

The User Datagram Protocol (UDP)

The User Datagram Protocol, or UDP, is another widely used transport protocol. It’s faster than TCP, but it is also less reliable. UDP does not make sure all packets are delivered and in order, and it doesn’t establish a connection before beginning or receiving transmissions.

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Network Protocol

In networking, a protocol is a standardized way of doing certain actions and formatting data so that two or more devices are able to communicate with and understand each other.

To understand why protocols are necessary, consider the process of mailing a letter. On the envelope, addresses are written in the following order: name, street address, city, state, and zip code. If an envelope is dropped into a mailbox with the zip code written first, followed by the street address, followed by the state, and so on, the post office won’t deliver it. There is an agreed-upon protocol for writing addresses in order for the postal system to work. In the same way, all IP data packets must present certain information in a certain order, and all IP addresses follow a standardized format.

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IP Address

IP Address (Internet Protocol address) is a 32-bit logical address for a host on a TCP/IP network (IPv4) or 128-bit (IPv6). Each host on a TCP/IP network needs a unique IP address for communication to take place reliably on the network.

IP addresses are usually expressed in four-octet, dotted-decimal form — w.x.y.z — in which each octet ranges in value from 0 to 255 (with some restrictions). The IP address of a host is partitioned by the network’s subnet mask into two parts, a network ID and a host ID.

IP addresses belong to certain classes according to their first octet, as defined in the following table. The actual distinguishing feature of each class is the pattern of high-order bits in the first octet, but it is easier to remember these classes by their first octet decimal numbers.

IP addresses whose first octet is 127 represent the loopback address and are used for troubleshooting purposes only, not for naming hosts.

Loopback Address

In TCP/IP networking, Loopback Address is the special IP address The loopback address is used to route outgoing IP packets to the TCP/IP protocol stack bound to the network interface card (NIC) and back to the source application without actually placing the packets on the network.

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IP Address Classes:

Networks are categorized into different classes, labeled A through E. Class A networks can connect millions of devices. Class B networks and Class C networks are progressively smaller in size. (Class D and Class E networks are not commonly used.)

Let’s break down how these classes affect IP address construction:

Class A network: Everything before the first period indicates the network, and everything after it specifies the device within that network. Using as an example, the network is indicated by “203” and the device by “0.113.112.”

Class B network: Everything before the second period indicates the network. Again using as an example, “203.0” indicates the network and “113.112” indicates the device within that network.

Class C network: For Class C networks, everything before the third period indicates the network. Using the same example, “203.0.113” indicates the Class C network, and “112” indicates the device.

Types of IP Addresses

There are two versions of IP, they are IPv4 and IPv6. IPv4 has been in use since the start of the Internet and is deployed across the Internet, and home / corporate networks. IPv4 uses 32 bits for addressing, however, due to the rapid growth of the Internet, all IPv4 addresses have been allocated (as of 2013).

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As IP6 rolls out they will also need to operate with two addresses until the migration is complete, and IP4 is discontinued. IP addresses are logical addresses, and are assigned by a network administrator or can be auto-assigned (using DHCP).

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Difference between Private and Public IP addresses

Both IPv4 and IPV6 have both public and private address ranges.
The private addresses are used for home/business networks and the addresses aren’t routable on the Internet i.e. They don’t travel across the internet. For IP4 the private addresses start with 10.x.x.x or 192.168.x.x or 172.16.x.x. Public addresses are reachable from anywhere on the internet and are routable.

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How does IP addressing work

An IP address is a unique identifier assigned to a device or domain that connects to the Internet. Each IP address is a series of characters, such as ‘’. Via DNS resolvers, which translate human-readable domain names into IP addresses, users are able to access websites without memorizing this complex series of characters.

Each IP packet will contain both the IP address of the device or domain sending the packet and the IP address of the intended recipient, much like how both the destination address and the return address are included on a piece of mail.

The Role of Dynamic Address Assignment

Dynamic address assignment provides several benefits to the administrator. It greatly reduces the time spent configuring clients, since the process occurs automatically across the network rather than having to visit each workstation. Instead, administrators spend their time configuring the database. It can also help prevent configuration problems such as duplicate address assignments or input errors. It may even provide a mechanism for recovering and reusing assigned addresses that are no longer being used.

A key feature of dynamic address assignment concerns the protocols that are used between the requesting client and the server that provides address information. These protocols define the process of obtaining configuration information. They specify the format of the packets used to convey information between client and server and may define the range of information that can be distributed to the client. The rest of this chapter will focus on these protocols.

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The Internet: Packets, Routing & Reliability

A node refers to a networking connection point where a connection occurs inside a network that further helps in receiving, transmitting, creating, or storing files or data.

Multiple devices could be connected to the Internet or network using wired or wireless nodes. To form a network connection, one requires two or more nodes where each node carries its unique identification to obtain access, such as an IP address. Some examples of nodes are computers, printers, modems, switches, etc.

Network Devices (Hub, Repeater, Bridge, Switch, Router, Gateways and Brouter)

Network devices, also known as networking hardware, are physical devices that allow hardware on a computer network to communicate and interact with one another. For example Repeater, Hub, Bridge, Switch, Routers, Gateway, Brouter, NIC, etc.

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A rack also called an equipment rack, is a metal frame for holding and organizing networking devices. A networking component that is designed to be mounted in a rack is said to be rack-mountable. Rack-mountable devices include hubs, routers, Ethernet switches, patch panels, and uninterruptible power supply (UPS) devices.

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Network routing is the process of selecting a path across one or more networks. The principles of routing can apply to any type of network, from telephone networks to public transportation. In packet-switching networks, such as the Internet, routing selects the paths for Internet Protocol (IP) packets to travel from their origin to their destination. These Internet routing decisions are made by specialized pieces of network hardware called routers.

A router is a physical networking device, which forwards data packets between networks. Routers do the data analysis, perform the traffic-directing functions on the network, and define the top route for the data packets to reach their destination node. A data packet may have to surpass multiple routers present within the network until it reaches its destination.

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In a computer network, a switch is a device that connects other devices and helps in node-to-node communication by deciding the best way of transmitting data within a network (usually if there are multiple routes in a more extensive network).

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Though a router also transmits information, it forwards the information only between networks, whereas a switch forwards data between nodes present in a single network.

Now Consider the image below. For a data packet to get from Computer A to Computer B, should it pass through networks 1, 3, and 5 or networks 2 and 4? The packet will take a shorter path through networks 2 and 4, but networks 1, 3, and 5 might be faster at forwarding packets than 2 and 4. These are the kinds of choices network routers constantly make.

The Main Routing Protocols

In networking, a protocol is a standardized way of formatting data so that any connected computer can understand the data. A routing protocol is a protocol used for identifying or announcing network paths.

The following protocols help data packets find their way across the Internet:

  1. IP: The Internet Protocol (IP) specifies the origin and destination for each data packet. Routers inspect each packet’s IP header to identify where to send them.
  2. BGP: The Border Gateway Protocol (BGP) routing protocol is used to announce which networks control which IP addresses, and which networks connect to each other. (The large networks that make these BGP announcements are called autonomous systems.) BGP is a dynamic routing protocol.

The below protocols route packets within an AS:

  1. OSPF: The Open Shortest Path First (OSPF) protocol is commonly used by network routers to dynamically identify the fastest and shortest available routes for sending packets to their destination.
  2. RIP: The Routing Information Protocol (RIP) uses “hop count” to find the shortest path from one network to another, where “hop count” means the number of routers a packet must pass through on the way. (When a packet goes from one network to another, this is known as a “hop.”)

Other interior routing protocols include EIGRP (the Enhanced Interior Gateway Routing Protocol, mainly for use with Cisco routers) and IS-IS (Intermediate System to Intermediate System).

How Does IP Routing Work

The Internet is made up of interconnected large networks that are each responsible for certain blocks of IP addresses; these large networks are known as autonomous systems (AS). A variety of routing protocols, including BGP, help route packets across ASes based on their destination IP addresses.

Routers have routing tables that indicate which ASes the packets should travel through in order to reach the desired destination as quickly as possible. Packets travel from AS to AS until they reach one that claims responsibility for the targeted IP address. That AS then internally routes the packets to the destination.

Protocols attach packet headers at different layers of the OSI model:

The 7 layers OSI model is a short name for the Open Systems Interconnection (OSI) reference model for networking. This theoretical model explains how networks behave within an orderly, seven-layered model for networked communication. The OSI model isn’t specific to a protocol suite and can be applied to most networking protocols past and present.

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In simple terms, Routers refer to internal routing tables to make decisions about how to route packets along network paths. A routing table records the paths that packets should take to reach every destination that the router is responsible for. Think of train timetables, which train passengers to consult to decide which train to catch. Routing tables are like that, but for network paths rather than trains.

Routers work in the following way: when a router receives a packet, it reads the headers of the packet to see its intended destination, like the way a train conductor may check a passenger’s tickets to determine which train they should go on. It then determines where to route the packet based on information in its routing tables.

Routers do this million times a second with millions of packets. As a packet travels to its destination, it may be routed several times by different routers.

Routing tables can either be static or dynamic. Static routing tables do not change. A network administrator manually sets up static routing tables. This essentially sets in stone the routes data packets take across the network unless the administrator manually updates the tables.

Dynamic routing tables update automatically. Dynamic routers use various routing protocols (see below) to determine the shortest and fastest paths. They also make this determination based on how long it takes packets to reach their destination — similar to the way Google Maps, Waze, and other GPS services determine the best driving routes based on past driving performance and current driving conditions.

Dynamic routing requires more computing power, which is why smaller networks may rely on static routing. But for medium-sized and large networks, dynamic routing is much more efficient.

Packets can take different routes to the same place if necessary, just as a group of people driving to an agreed-upon destination can take different roads to get there.

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IP Header

IP header is meta information at the beginning of an IP packet. It displays information such as the IP version, the packet’s length, the source, and the destination.

IPV4 header format is 20 to 60 bytes in length. It contains information needed for routing and delivery. It consists of 13 fields such as Version, Header length, total distance, identification, flags, checksum, source IP address, and destination IP address. It provides essential data need to transmit the data. LE.

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IP Packet

IP packets are created by adding an IP header to each packet of data before it is sent on its way.

An IP header is just a series of bits (ones and zeros), and it records several pieces of information about the packet, including the sending and receiving of an IP address.

IP headers also report:

  • Header length
  • Packet length
  • Time To Live (TTL), or the number of network hops a packet can make before it is discarded

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  • Which transport protocol is being used (TCP, UDP, etc.)

In total there are 14 fields for information in IPv4 headers, although one of them is optional.

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Network ID

Network ID is the portion of an IP address that identifies the TCP/IP network on which a host resides. The network ID portion of an IP address uniquely identifies the host’s network on an internetwork, while the host ID portion of the IP address identifies the host within its network.

Together, the host ID and network ID, which make up the entire IP address of a host, uniquely identify the host on a TCP/IP internetwork.


The Host ID is the portion of an IP address that uniquely identifies a host on a given TCP/IP network. You find the host ID by logically NANDing the binary form of the IP address with the binary form of the subnet mask for the network. The other part of an IP address is the network ID, which specifies the network to which the host belongs.

Subnet & Subnetting

A subnet, or subnetwork, is a network inside a network. Subnets make networks more efficient. Through subnetting, network traffic can travel a shorter distance without passing through unnecessary routers to reach its destination.

Subnet Mask

A subnet mask is like an IP address, but for only internal usage within a network. Routers use subnet masks to route data packets to the right place. Subnet masks are not indicated within data packets traversing the Internet — those packets only indicate the destination IP address, which a router will match with a subnet.

Suppose Bob answers Alice’s letter, but he sends his reply to Alice’s place of employment rather than her home. Alice’s office is quite large with many different departments. To ensure employees receive their correspondence quickly, the administrative team at Alice’s workplace sorts mail by department rather than by an individual employee. After receiving Bob’s letter, they look up Alice’s department and see she works in Customer Support. They send the letter to the Customer Support department instead of to Alice, and the customer support department gives it to Alice.

In this analogy, “Alice” is like an IP address and “Customer Support” is like a subnet mask. By matching Alice to her department, Bob’s letter was quickly sorted into the right group of potential recipients. Without this step, office administrators would have to spend time laboriously looking for the exact location of Alice’s desk, which could be anywhere in the building.

For a real-world example, suppose an IP packet is addressed to the IP address This IP address is a Class C network, so the network is identified by “192.0.2” (or to be technically precise, Network routers forward the packet to a host on the network indicated by “192.0.2.”

Once the packet arrives at that network, a router within the network consults its routing table. It does some binary mathematics using its subnet mask of, sees the device address “15” (the rest of the IP address indicates the network), and calculates which subnet the packet should go to. It forwards the packet to the router or switches responsible for delivering packets within that subnet, and the packet arrives at IP address (learn more about routers and switches).


Subnetting is the process of partitioning a single TCP/IP network into a number of separate networks called subnets. These subnets are then joined using routers. Advantages of subnetting a network include the following:

  • Reducing network congestion by limiting the range of broadcasts using routers
  • Enabling different networking architectures to be joined

Why is subnetting necessary?

As the previous example illustrates, the way IP addresses are constructed makes it relatively simple for Internet routers to find the right network to route data into. However, in a Class A network (for instance), there could be millions of connected devices, and it could take some time for the data to find the right device. This is why subnetting comes in handy: subnetting narrows down the IP address to usage within a range of devices.

Because an IP address is limited to indicating the network and the device address, IP addresses cannot be used to indicate which subnet an IP packet should go to. Routers within a network use something called a subnet mask to sort data into subnetworks.

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A Port

A port is a virtual point where network connections start and end. Ports are software-based and managed by a computer’s operating system. Each port is associated with a specific process or service. Ports allow computers to easily differentiate between different kinds of traffic: emails go to a different port than webpages, for instance, even though both reach a computer over the same Internet connection.

A Port Number

Ports are standardized across all network-connected devices, with each port assigned a number. Most ports are reserved for certain protocols — for example, all Hypertext Transfer Protocol (HTTP) messages go to port 80. While IP addresses enable messages to go to and from specific devices, port numbers allow targeting of specific services or applications within those devices.

What are the different port numbers?

There are 65,535 possible port numbers, although not all are in common use. Some of the most commonly used ports, along with their associated networking protocol, are:

  1. Ports 20 and 21: File Transfer Protocol (FTP). FTP is for transferring files between a client and a server.
  2. Port 22: Secure Shell (SSH). SSH is one of many tunneling protocols that create secure network connections.
  3. Port 25: Historically, Simple Mail Transfer Protocol (SMTP). SMTP is used for email.
  4. Port 53: Domain Name System (DNS). DNS is an essential process for the modern Internet; it matches human-readable domain names to machine-readable IP addresses, enabling users to load websites and applications without memorizing a long list of IP addresses.
  5. Port 80: Hypertext Transfer Protocol (HTTP). HTTP is the protocol that makes the World Wide Web possible.
  6. Port 123: Network Time Protocol (NTP). NTP allows computer clocks to sync with each other, a process that is essential for encryption.
  7. Port 179: Border Gateway Protocol (BGP). BGP is essential for establishing efficient routes between the large networks that make up the Internet (these large networks are called autonomous systems). Autonomous systems use BGP to broadcast which IP addresses they control.
  8. Port 443: HTTP Secure (HTTPS). HTTPS is the secure and encrypted version of HTTP. All HTTPS web traffic goes to port 443. Network services that use HTTPS for encryption, such as DNS over HTTPS, also connect at this port.
  9. Port 500: Internet Security Association and Key Management Protocol (ISAKMP), which is part of the process of setting up secure IPsec connections.
  10. Port 587: Modern, secure SMTP that uses encryption.
  11. Port 3389: Remote Desktop Protocol (RDP). RDP enables users to remotely connect to their desktop computers from another device.

The Internet Assigned Numbers Authority (IANA) maintains the full list of port numbers and protocols assigned to them.

Internet Service Provider (ISP)

ISP is a company that provides individual users and businesses with connectivity to the Internet. Internet service providers (ISPs) also provide clients with access to Internet services such as Web hosting, Simple Mail Transfer Protocol (SMTP) mail, Usenet newsgroups, Internet Relay Chat (IRC), and downloadable Internet software.

ISPs come in various shapes and sizes, from volunteer-run freenets to local, regional, and national service providers such as America Online. Many smaller ISPs, especially those that originated in a university environment, still use freely available software such as Linux, Apache’s Web server, and Sendmail for providing services to customers.

Larger ISPs often use a heterogeneous network in which Internet Information Services (IIS) and Microsoft Exchange Server play an essential role by providing core Web and mail services, as well as support for advanced Web and e-commerce applications for business and corporate clients.

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Domains vs Workgroups

Computers on a network can be part of a workgroup or a domain. The main difference between workgroups and domains is how resources on the network are managed. Computers on home networks are usually part of a workgroup, and computers on workplace networks are usually part of a domain.

In a workgroup:

  • All computers are peers; no computer has control over another computer.
  • Each computer has a set of user accounts. To use any computer in the workgroup, you must have an account on that computer.
  • There are typically no more than ten to twenty computers.
  • All computers must be on the same local network or subnet.

In a domain:

  • One or more computers are servers. Network administrators use servers to control the security and permissions for all computers on the domain. This makes it easy to make changes because the changes are automatically made to all computers.
  • If you have a user account on the domain, you can log on to any computer on the domain without needing an account on that computer.
  • There can be hundreds or thousands of computers.
  • The computers can be on different local networks.

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Domain Name

The domain name is the most prominent part of a web address. Typically, different pages on the same site will continue to use the same domain name.

Each segment of the domain name separated by a period is called a domain. The domain on the right is called a top-level domain, with the domain to the left of it called the second-level domain, then the third-level domain, and so on.

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Domain Controller

A domain controller is a server responsible for managing network and identity security requests. It acts as a gatekeeper and authenticates whether the user is authorized to access the IT resources in the domain. The Microsoft Windows Active Directory Server hierarchically organizes and protects user information, business-critical data, and IT devices operating on the network.

The primary function of domain controllers is to authenticate and validate users on a network, including group policies, user credentials, and computer names to determine and validate user access.

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An Active Directory

Active Directory is a framework that manages several Windows server domains. In contrast, a domain controller is a server on Active Directory to authenticate users based on centrally stored data. Each Active Directory forest can have multiple domains. The role of domain controllers is to manage trust among the domains by granting access to users from one domain to the other via a proper security authentication process. System administrators can also set complex security policies via domain controllers.

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How does Active Directory work?

Active Directory offers a set of services for administrators to manage their IT networks. These services are deployed on a Windows server called a domain controller. Active Directory Domain Services (AD DS) is the most widely used Active Directory service. It authenticates Active Directory objects and authorizes access to network resources. AD DS also stores and organizes data in a logical, hierarchical structure and can be managed from anywhere in the network. Other important AD services include Active Directory Federation Services (AD FS), Active Directory Certification Services (AD CS), Active Directory Lightweight Directory Services (AD LDS), and Active Directory Rights Management Services (AD RMS).

Read on to learn more about Active Directory and its services.

Group Policy (GPO) in an Active Directory

A Group Policy Object (GPO) is a group of settings that are created using the Microsoft Management Console (MMC) Group Policy Editor. GPOs can be associated with single or numerous Active Directory containers, including sites, domains, or organizational units (OUs). The MMC allows users to create GPOs that define registry-based policies, security options, software installation, and much more.

Active Directory applies GPOs in the same, logical order; local policies, site policies, domain policies, and OU policies. GPOs that are in nested OUs work from the OU closest to the root first and outwards from there.

Read on to learn more about GPO

Differences between a domain controller and an Active Directory

  • Domain Controller: Every system has its local accounts. IT administrators need to manage and configure such user accounts centrally. Centrally managed accounts can also access network resources. To ensure authenticated accounts use the network resources, domain controllers verify and validate them. This helps protect your network from unauthorized user access and ensures only relevant users have network access.
  • Active Directory: Active Directory was introduced by Microsoft for centralized domain management. This database enables users to connect with network resources to get their work done. It can store huge volumes of data as objects organized as forests, trees, and domains. It also includes other services such as permission access rights management, Single Sign-On (SSO), security certificates for public-key cryptography, and Lightweight Directory Access Protocol (LDAP).

The Domain Name System (DNS)

The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like or Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6).

How does DNS work?

The host requests for the IP address of a particular domain name to the DNS server and the IP address is returned to the host by the DNS server. The hierarchy of the resolution of the request is shown below.

  1. The client requests for the IP address of a particular domain name to the DNS resolver.
  2. The resolver requests to the root DNS server.
  3. The root DNS server then forwards the query to the Top-level DNS server.
  4. The top-level domain server has all the information about the authoritative DNS servers.
  5. The authoritative server then returns the IP address corresponding to the requested domain name to the resolver.
  6. The resolver then returns the IP address to the host.

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Dynamic Host Configuration Protocol (DHCP)

Dynamic Host Configuration Protocol (DHCP) is a client/server protocol that automatically provides and assigns IP addresses, default gateways and other network parameters to client devices. It relies on the standard protocol known as Dynamic Host Configuration Protocol or DHCP to respond to broadcast queries by clients.

A DHCP server automatically sends the required network parameters for clients to properly communicate on the network. Without it, the network administrator has to manually set up every client that joins the network, which can be cumbersome, especially in large networks. DHCP servers usually assign each client with a unique dynamic IP address, which changes when the client’s lease for that IP address has expired.

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Remote Desktop Protocol (RDP)

Remote Desktop Protocol (RDP) is a protocol used by the Microsoft Windows Server family that lets clients communicate with Terminal Services over a network.

Remote Desktop Protocol (RDP) is based on the T.120 protocol of the International Telecommunication Union (ITU), a standard multichannel conferencing protocol that was also used in Microsoft NetMeeting conferencing software.

RDP is a multichannel-capable protocol that can use separate virtual channels for carrying serial device communication and presentation data sent from the server and encrypted client mouse and keyboard data sent from the client.

RDP supports up to 64,000 separate channels for data transmission and supports multipoint transmission.

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Final Thought:

So basically, everything that you do on the internet involves computer networking.



Writer | network engineer | Traveler | Biker | Polyglot. I’m so deep even the ocean gets jealous

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Raja Muhammad Mustansar Javaid

Writer | network engineer | Traveler | Biker | Polyglot. I’m so deep even the ocean gets jealous