WHAT IS A NETWORK OR IP ADDRESS?

An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer networkAn Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.An IP address serves two main functions: host or network interface identification and location addressing.

The IP address space is managed globally by the Internet Assigned Numbers Authority (IANA), and by five regional Internet registries (RIRs) responsible in their designated territories for assignment to local Internet registries, such as Internet service providers, and other end users. IPv4 addresses were distributed by IANA to the RIRs in blocks of approximately 16.8 million addresses each, but have been exhausted at the IANA level since 2011. Only one of the RIRs still has a supply for local assignments in Africa. Some IPv4 addresses are reserved for private networks and are not globally unique.

IP addresses are written and displayed in human-readable notations, such as 172.16.254.1 in IPv4, and 2001:db8:0:1234:0:567:8:1 in IPv6. The size of the routing prefix of the address is designated in CIDR notation by suffixing the address with the number of significant bits, e.g., 192.168.1.15/24, which is equivalent to the historically used subnet mask 255.255.255.0.

Each network that runs TCP/IP must have a unique network number. Every machine on the network must have a unique IP address. You must understand how IP addresses are constructed before you register your network and obtain its network number. This section describes IPv4 addresses. For information on IPv6 addresses, see IPv6 Addressing. The IPv4 address is a 32-bit number that uniquely identifies a network interface on a machine. An IPv4 address is typically written in decimal digits, formatted as four 8-bit fields that are separated by periods. Each 8-bit field represents a byte of the IPv4 address. This form of representing the bytes of an IPv4 address is often referred to as the dotted-decimal format.

Network administrators assign an IP address to each device connected to a network. Such assignments may be on a static (fixed or permanent) or dynamic basis, depending on network practices and software features.

2 TYPES OF IP VERSIONS

Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. However, because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP (IPv6), using 128 bits for the IP address, was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s.

The bytes of the IPv4 address are further classified into two parts: the network part and the host part. The following figure shows the component parts of a typical IPv4 address, 129.144.50.56.

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion. IPv6 is intended to replace IPv4. In December 1998, IPv6 became a Draft Standard for the IETF who subsequently ratified it as an Internet Standard on 14 July 2017.

Devices on the Internet are assigned a unique IP address for identification and location definition. With the rapid growth of the Internet after commercialization in the 1990s, it became evident that far more addresses would be needed to connect devices than the IPv4 address space had available. By 1998, the Internet Engineering Task Force (IETF) had formalized the successor protocol. IPv6 uses a 128-bit address, theoretically allowing 2128, or approximately 3.4×1038 addresses. The actual number is slightly smaller, as multiple ranges are reserved for special use or completely excluded from use. The two protocols are not designed to be interoperable, and thus direct communication between them is impossible, complicating the move to IPv6. However, several transition mechanisms have been devised to rectify this.

IPv6 provides other technical benefits in addition to a larger addressing space.In particular, it permits hierarchical address allocation methods that facilitate route aggregation across the Internet, and thus limit the expansion of routing tables. The use of multicast addressing is expanded and simplified, and provides additional optimization for the delivery of services. Device mobility, security, and configuration aspects have been considered in the design of the protocol.

IPv6 addresses are represented as eight groups, separated by colons, of four hexadecimal digits. The full representation may be simplified by several methods of notation; for example, 2001:0db8:0000:0000:0000:8a2e:0370:7334 becomes 2001:db8::8a2e:370:7334.

Classes of IP Address

TCP/IP defines five classes of IP addresses: class A, B, C, D, and E. Each class has a range of valid IP addresses. The value of the first octet determines the class. IP addresses from the first three classes (A, B and C) can be used for host addresses. The other two classes are used for other purposes – class D for multicast and class E for experimental purposes.

The system of IP address classes was developed for the purpose of Internet IP addresses assignment. The classes created were based on the network size. For example, for the small number of networks with a very large number of hosts, the Class A was created.The Class C was created for numerous networks with small number of hosts.

Classes of IP addresses are:

For the IP addresses from Class A, the first 8 bits (the first decimal number) represent the network part, while the remaining 24 bits represent the host part. For Class B, the first 16 bits (the first two numbers) represent the network part, while the remaining 16 bits represent the host part. For Class C, the first 24 bits represent the network part, while the remaining 8 bits represent the host part.

Sources: https://en.wikipedia.org/wiki/IP_address
               https://en.wikipedia.org/wiki/IPv4
               https://en.wikipedia.org/wiki/IPv6
               https://study-ccna.com/classes-of-ip-addresses/

WHAT IS THE DIFFERENCE BETWEEN STRAIGHT-THROUGH AND CROSSOVER CABLE?

Straight-through Cable

Is a type of twisted pair copper wire cable for local area network (LAN) use for which the RJ-45 connectors at each end have the same pinout (i.e., arrangement of conductors). It is identical to crossover cable, except that in the latter the wires on the cable are crossed over so that the receive signal pins on the connector on one end are connected to the transmit signal pins on the connector on the other end. Straight-through cable is also commonly referred to as patch cable. However, this might be confusing in some situations because patch cable also has a broader definition that emphasizes the fact that there is a connector on each end rather than the equality (or lack thereof) of the pinouts. Straight-through cable is used to connect computers and other end-user devices (e.g., printers) to networking devices such as hubs and switches. It can also be used to directly connect like devices (e.g., two hubs or two switches) if the cable is plugged into an uplink port on one (but not both) of the devices. Crossover cable is used to connect two like devices without the use of an uplink port.

Crossover Cable

Is a crossover cable for Ethernet used to connect computing devices together directly. It is most often used to connect two devices of the same type, e.g. two computers (via their network interface controllers) or two switches to each other. By contrast, patch cables or straight through cables are used to connect devices of different types, such as a computer to a network switch or Ethernet hub.

Intentionally crossed wiring in the crossover cable connects the transmit signals at one end to the receive signals at the other end.


Many devices today support auto MDI-X capability, wherein a patch cable can be used in place of a crossover cable, or vice versa, and the receive and transmit signals are reconfigured automatically within the devices to yield a working connection.

WHAT ARE THE TYPES OF CABLE?

Twisted Pair - is the ordinary copper wire that connects home and many business computers to the telephone company. To reduce crosstalk or electromagnetic induction between pairs of two wires, two insulated copper wires are twisted around each other.

TWO TYPES OF TWISTED PAIR:

 1. Shielded Twisted Pair - was originally designed by IBM for token ring networks that include two individual wires covered with a foil shielding, which prevents electromagnetic interference, thereby transporting data faster.

2. Unshielded Twisted Pair -  one of the least expensive wires and works for basic needs of phone systems, so it is one of the commonly installed in residential industries.

Coaxial Cable - is a type of copper cable specially built with a metal shield and other components engineered to block signal interference. It is primarily used by cable TV companies to connect their satellite antenna facilities to customer home and businesses.

Fiber Optic Cable - also known as optical fiber cable, is an assembly similar to an electrical cable, but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed.

WHAT ARE THE DIFFERENT NETWORKING DEVICES?

Hub

- is the most common networking device that connects multiple computers or other network devices together.

Switch

-  is networking hardware that connects devices on a computer network by using packet switching to receive, and forward data to the destination device.

Router

- is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent through the internet, such as a web page or email, is in the form of data packets.

Bridge

- is a type of computer network device that provides interconnection with other bridge networks that use the same protocol. Bridge devices work at the data link layer of the Open System Interconnect (OSI) model, connecting two different networks together and providing communication between them.

Network Interface Card

-  is a computer hardware component that connects a computer to a computer network. Early network interface controllers were commonly implemented on expansion cards that plugged into a computer bus.

Modem

- is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves.

Transceivers

- is a hardware device designed to connect computers or electronic devices within a network, allowing them to transmit and receive messages. A transceiver consists of a transmitter and a receiver, hence the name. An Ethernet transceiver is also known as a media access unit (MAU).

Firewall

- is a system designed to prevent unauthorized access to or from a private network. You can implement a firewall in either hardware or software form, or a combination of both. Firewalls prevent unauthorized internet users from accessing private networks connected to the internet, especially intranets.

WHAT IS A NETWORK TOPOLOGY?

Network Topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

Network topology is the topological structure of a network and may be depicted physically or logically. It is an application of graph theory wherein communicating devices are modeled as nodes and the connections between the devices are modeled as links or lines between the nodes.

Linear Bus Topology

Linear Bus Topology is a type of network topology in which each device is connected one after the other in a sequential chain. In this case, the bus is the network connection between the devices, and if any link in the network chain is severed, all network transmission is halted.

Advantages of Bus Topology

• It works well when you have a small network.
• It's the easiest network topology for connecting computers or peripherals in a linear fashion.
• It requires less cable length than a star topology.

Disadvantages of Bus Topology

• It can be difficult to identify the problems if the whole network goes down.
• It can be hard to troubleshoot individual device issues.
• Bus topology is not great for large networks.
• Terminators are required for both ends of the main cable.
• Additional devices slow the network down.
• If a main cable is damaged, the network fails or splits into two.

Star Topology

Star Topology Alternatively referred to as a star network, star topology is one of the most common network setups. In this configuration, every node connects to a central network device, like a hub, switch, or computer. The central network device acts as a server and the peripheral devices act as clients. Depending on the type of network card used in each computer of the star topology, a coaxial cable or an RJ-45 network cable is used to connect computers together. The image shows how this network setup gets its name, as it is shaped like a star.

Advantages of Star Topology

• Centralized management of the network, through the use of the central computer, hub, or switch.
• Easy to add another computer to the network.
• If one computer on the network fails, the rest of the network continues to function normally.

Disadvantages of Star Topology

• May have a higher cost to implement, especially when using a switch or router as the central network device.
• The central network device determines the performance and number of nodes the network can handle.
• If the central computer, hub, or switch fails, the entire network goes down and all computers are disconnected from the network.

Ring Topology

Ring Topology is a network configuration in which device connections create a circular data path. Each networked device is connected to two others, like points on a circle. Together, devices in a ring topology are referred to as a ring network.

In a ring network, packets of data travel from one device to the next until they reach their destination. Most ring topologies allow packets to travel only in one direction, called a unidirectional ring network. Others permit data to move in either direction, called bidirectional.

The major disadvantage of a ring topology is that if any individual connection in the ring is broken, the entire network is affected.

Ring topologies may be used in either LANs (local area networks) or WANs (wide area networks). Depending on the type of network card used in each computer of the ring topology, a coaxial cable or an RJ-45 network cable is used to connect computers together.

Advantages of Ring Topology

• All data flows in one direction, reducing the chance of packet collisions.
• A network server is not needed to control network connectivity between each workstation.
• Data can transfer between workstations at high speeds.
• Additional workstations can be added without impacting performance of the network.

Disadvantages of Ring Topology

• All data being transferred over the network must pass through each workstation on the network, which can make it slower than a star topology.
• The entire network will be impacted if one workstation shuts down.
• The hardware needed to connect each workstation to the network is more expensive than Ethernet cards and hubs/switches.

Mesh Topology

Mesh Topology is a type of networking where all nodes cooperate to distribute data amongst each other. This topology was originally developed 30+ years ago for military applications, but today, they are typically used for things like home automation, smart HVAC control, and smart buildings.

Advantages of a Mesh Topology

• Manages high amounts of traffic, because multiple devices can transmit data simultaneously.
• A failure of one device does not cause a break in the network or transmission of data.
• Adding additional devices does not disrupt data transmission between other devices.

Disadvantages of a Mesh Topology

• The cost to implement is higher than other network topologies, making it a less desirable option.
• Building and maintaining the topology is difficult and time consuming.
• The chance of redundant connections is high, which adds to the high costs and potential for reduced efficiency.

Hybrid Topology

A hybrid topology is a type of network topology that uses two or more differing network topologies. These topologies include a mix of bus topology, mesh topology, ring topology, star topology, and tree topology.

Advantages of a Hybrid Topology

• Reliable : It has far better fault tolerance. The section where fault is found could possibly be singled out from the rest of network and required restorative steps could be taken, without impacting the working of rest of the network.
• Effective: The most important advantage of this topology is that the weakness of the different topologies connected are disregarded and only the strengths are taken into consideration. For instance, ring topology has good data reliability and star topology has high tolerance capability, so these two function quite well in hybrid star-ring topology.
• Flexible: One of the key advantages of this topology is its flexibility. The topology is created, so that it can be implemented for a variety of distinct network environment. Hybrid Network can be created in line with the demands of the corporation and by maximizing the available resources.
• Scalable: Hybrid networks are built in a fashion which enables for easy integration of new hardware components like additional concentration points. It’s quite simple to extend the size of network with the addition of new elements, without disturbing existing architecture.

Disadvantages of a Hybrid Topology

• Complexity: Due to the fact that different topologies connect in a hybrid topology, managing the topology gets challenging.. Its not easy to design this type of architecture and its a difficult job for designers. Configuration and installation process needs to be very efficient.
• Expensive: The network hubs needed for hybrid topology networking are costly to purchase and maintain. The cost of this topology is higher in comparison to the other topologies. The hubs used to connect two distinct networks are expensive. These hubs are not the same as usual hubs since they have to be smart enough to work with different architectures and should be able to operate even when a portion of network is down. As hybrid architectures are usually larger in scale, they may require a lot of cables, advanced network devices, etc.

Sources: https://en.wikipedia.org/wiki/Network_topology

               https://www.computerhope.com/jargon/l/linear-bus-topology.htm

              

               https://www.link-labs.com/blog/what-is-mesh-topology

       

               https://www.computerhope.com/jargon/m/mesh.htm

         

               https://www.computerhope.com/jargon/r/ringtopo.htm

               https://www.computerhope.com/jargon/h/hybrtopo.htm

            

               https://www.computerhope.com/jargon/b/bustopol.htm

           https://universalteacher.com/1/advantages-and-disadvantages-of-hybrid-topology/

How To Be A Responsible Netizen

What is a netizen?
 The term netizen is a portmanteau of the words Internet and citizen, as in a "citizen of the net" or "net citizen." It describes a person actively involved in online communities or the Internet in general.

Here are 6 ways to be a responsible netizen...

1. Be aware of what you post online. 
Facebook, Twitter, or Instagram are just some of the social networking sites people can join and use. It may seem to be a great way to drop off frustrations and may be fun to use, but make sure to do it responsibly. Before posting online, ask yourself if what is the tone of your post like? Is it true? Does it cause harm to someone else? Or is it worth sharing? Remember that everything you post online can put you at risk or can harm someone else. So, be a smart netizen.

2. Be careful of what you say. 
Be attentive to the fact that you won’t appear rude, insensitive, arrogant, or sly. A hastily written bad comment can cause future embarrassment and remains there forever. Hence, be polite and be more mature when interacting with your friends, followers and audience on social media.

3. Do not engage in cyberbullying and other internet crimes. 
It’s okay to act cool in social media, but getting involved in serious crimes like cyberbullying or stealing someone’s identity is not good. Never criticize a particular person without knowing the real reason behind the issue.

4. Recognize and respect diversity. 
When you are interacting with people online, it also means that you are talking to people with different cultures, behaviors, and perspectives in life. Thus, it is important to understand and respect the opinions of others, especially in the virtual world.

5. Be a human. 
It can be easy to forget that you are talking to real people and not computers when you’re behind the screen. So always remember that there is another person on the other side. They also have feelings so be careful what you say, don’t be judgmental, and respect each others point of view.

6. Credit the source when reposting. 
Always credit the creator when sharing someone else’s words, pictures, or other forms of intellectual property.  This is a sign of respect and honor to the person who made it.

These are some tips or ways to be a responsible netizen. Always keep in mind that every little thing that you do reflects who you are as a person. :)

Source: https://en.wikipedia.org/wiki/Netizen
             https://inspiringtips.com/ways-to-be-a-better-netizen/

WHAT IS A COMPUTER NETWORK?

Computer Network - is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections (data links) between nodes. These data links are established over cable media such as wires or optic cables, or wireless media such as Wi-Fi.

Advantages and Disadvantages of Networking

Advantages

Reduced Costs - Everyone in your home or office can share as single printer and a single high- speed Internet connection at the same time.

Increased Efficiency - You can access data, pictures, and many other files on any connected computer

Economical - Purchasing software network licenses is relatively cheaper than purchasing individual licenses

More Productivity - Shared internet access means no one needs to wait to use the Internet or email.

Everyone can work simultaneously.

Increased Access To Communication Channels - You can communicate with others in the network using the email or an Instant Messaging (IM) software.

More Efficient Patching of Software - Software updates need only be installed once. A patch is a piece of software designed to fix or update the data of a computer program.

    Disadvantages:

Network Failure - Some of the organization’s activities depend on the network to be up and running. If the network fails, the users lose access to information and the ability to communicate electronically.

Server Error - In a server/client relationship network, server faults may prevent you from using some application, or even from accessing your computer.

 Open to Hackers -Your system is open to hackers, especially if it is connected to internet at all times.

Open to Viruses - Networks are vulnerable to virus attacks. A virus introduced in a one workstation can be spread quickly to other workstations.

Location - Resources, such as printers, might be located to far from your table.


Network Media Types

Wireless Network - This is quickly becoming the connection option of choice as it does not require any cables to be set in your home or office.

Wired Network - Are typically used at the network core to interconnect servers and network equipment.

Types of Network

PAN: Personal Area Network - Is a computer network used to interconnect devices centered on an individual workplace.

LAN: Local Area Network - Is a type of network where two to as much as hundreds of computers are connected with each other using a network sharing device known as hub or switch.

MAN: Metropolitan Area Network - Is a larger network than LAN. It involves connecting several networks together that reside within a city, town or metropolis.

WAN: Wide Area Network - Is simply a network consisting of interconnected LANs. It is usually dispersed over a very wide area.

Source: https://en.wikipedia.org/wiki/Computer_network