Domain Name System explained

len Alfred Ajibola - 02nd September, 2022 @ 10:54 AM

Topics in ICT

Introduction to routers in networking Wired router and wireless router explained What are core routers in networking? Virtual routers explained with its configuration Edge router explained with its types Domain Name System explained Types of computer network Functions of a router Computer scheme of work, SS1, First Term Computer scheme of work, SS1, Second Term Computer scheme of work, SS1, Third Term Introduction to computer networks Types of DNS server Open Systems Interconnect: Layers of the OSI Model Internet of Things (IoT), How IoT works, its advantages and challenges How to consume less data on android phone Best programming languages to learn The internet and world wide web explained Computer Hardware, Parts and Functions of Computer Hardware

Academic Questions in ICT

Please click here to see all Questions and Answers

DNS belongs to layer _____ of the Open System Interconnect (OSI) model of networking.

  • A. One

  • B. Two

  • C. Three

  • D. Four

  • E. Five

  • F. Six

  • G. Seven

Which of the following DNS servers receive queries directly from computers, phones and other client devices?

  • A. Root Nameserver

  • B. Top Level Domain (TLD) Nameserver

  • C. Bottom Level Domain (BLD) Nameserver

  • D. Authoritative Nameserver

  • E. Direct Nameserver

  • F. Recursive DNS Server

The uppermost layer of the Open System Interconnect (OSI) model of networking is the _____ layer.

  • A. Physical

  • B. Application

  • C. Network

  • D. Transport

  • E. Data Link

  • F. Presentation

Concerning the internet of things, which of the following statement is incorrect?

  • A. Humans will become connected to the internet through the internet of things

  • B. It refers to the billions of physical devices that will be connected to the internet

  • C. Big data is associated with the internet of things

  • D. Presently, we have more humans living on earth that things connected to the internet

  • E. China, North America and Europe accounts for over two thirds of internet connected things

  • F. The ultimate goal of the Internet of things will be made a reality through IPv6

What is the first step towards disabling automatic image download on WhatsApp?

  • A. Click on the three dots on the top right hand corner

  • B. Click on the WhatsApp logo

  • C. Click on the settings icon on the top right corner

  • D. Click on the settings icon located on the to top-center of the app

  • E. Click directly on the storage and data icon located on the top right corner

  • F. Click on the mobile data usage icon located on the top right corner

The followings are ways to conserve data on android phones except _____.

  • A. Turning on data saving mode

  • B. Activating background apps

  • C. Use of Wi-Fi to update apps

  • D. Disable automatic image download on WhatsApp

  • E. Watch low resolution videos on youtube

  • F. Utilizing a reputable data saving app on google playstore

Twitter was launched in _____.

  • A. 2003

  • B. 2004

  • C. 2005

  • D. 2006

  • E. 2007

  • F. 2008

Due to the limitation of the Internet Protocol version 4 address, _____ was created.

  • A. IPv5

  • B. IPv6

  • C. IPv7

  • D. IPv8

  • E. IPv9

  • F. IPv10

Domain Name System (DNS):

Let me begin by stating that there are at least two ways to get to this website (Len Academy).

Apparently, the first and recommended way is to enter 'len.com.ng' on your web browser and you will be directed to this website (Len Academy). This is an easier method and apparently, the normal route to follow.

A second way is by typing some four sets of numbers separated by dots. This set of numbers is termed an IP Address. An instance is ''. This method is a more technical route to follow, and is usually not recommended to internet users. However, professional networking engineers may access a network via this route for troubleshooting purposes.

Interestingly, the above paragraph (second way) is the ideal route that the internet is meant to work because IP address is the protocol of the internet. This is what the founders of the internet used in designing the internet’s connectivity.

The term 'IP Address' means Internet Protocol Address and this is found at the network layer of the OSI model.

Please read on the network layer of the OSI model here.

Now, if we had gone with the second way from the above paragraph, the internet in itself will become quite difficult for almost everyone to use because it wouldn’t be fun memorizing the billions of available IP addresses. In fact, the internet professionals knew this potential problem and thus decided to come up with the Domain Name System in 1983.

Please read the notable dates on internet evolution here.

Consider the following notable points:

  • This website on which you are on (len.com.ng) is ideally an IP address. However, the important thing here is the fact that you don’t need to know the IP address of Len Academy in order to access the website.

  • All you need know is the domain name for Len Academy's IP Address; and that's 'len.com.ng'. This is made possible via the Domain Name System or DNS.

  • The DNS is a protocol that translates a domain name into an IP address. You may simply consider it as the phonebook of the internet.

  • Simple put, consider the concept of a domain name as the name of a website. In this regard, len.com.ng is a domain name, google.com is a domain name, yahoo.com is a domain name and so on.

It is noteworthy to state that DNS works at layer seven or Application layer of the OSI model of networking and layer four of the TCP/IP stack.

Please read on the OSI model here.


How DNS works

When you type in your destination website (for instance, len.com.ng) on your computer or phone browser's Uniform Resource Locator (URL), your browser will attempt to first resolve the entered web address (len.com.ng) to its specific IP address.

Note: Always understand that routing on the internet is a function an IP address and technically not the domain name which you had entered.

Please read on routers and routing here.

After your computer or phone does a successful domain lookup; that is, searches for the IP address that had been mapped to the domain name (len.com.ng), the IP address that matches 'len.com.ng' is henceforth used to get you the web page contained in len.com.ng.

After the domain name (len.com.ng in this instance) had been resolved to an IP address via the domain name system, the DNS is therefore done with its job since that’s specifically what it was created to do: 'to resolve domain names to a corresponding IP address'. In this regard, len.com.ng could now be resolved to something like (IP address) or the newer complex IPv6 address that looks something like '1201:bca0:11aa:1992::1:100b'.

The analogy as explained above indicates how all websites are accessed.

The point is: with DNS, you are more likely to remember len.com.ng or google.com or yahoo.com rather than some sets of numbers separated by dots (IP Address or IPv6 Address).

Please read on the types of DNS server here.

Again, think of it this way: You make use of names to save phone numbers so that you can easily recognize the owners of such numbers right? The same goes for DNS in mapping domain names to IP addresses; since one can easily remember domain names in comparison to IP addresses.

Another question is: 'what if the domain name that was entered is incorrect?'. As an instance, let’s say 'len.cm.ng' was entered by a user instead of 'len.com.ng'.

To answer the above question, since 'len.cm.ng' isn't matched to any IP Address, that will imply that 'len.cm.ng' cannot be resolved to any IP address. In this regard, the browser will respond with an error message, while also giving you some suggestions on how to go about the issue.

Below is an error message from an internet explorer browser:

Browser Error Message - Len Academy

Note: We have got millions of DNS servers around the world. If one of the servers doesn't know how to translate a specific domain name, it will question the next server until the appropriate IP address for such domain name is returned.

Please read on the internet of things (IoT) here.

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  • Online training on the academic subjects: biology, chemistry and basic science.

  • If you require an advanced smart school management system (web application) for your school.

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Amazing facts in ICT

1,000 computers are used to retrieve the answers to your Google search (query) in 0.2 seconds

The first hand-held mobile phone call was made in New York City on April 3rd, 1973

The logo for gmail was designed the night before it was launched

Coca Cola owns all the domain names (website names) that can be read as ahh. They include: ahh.com, ahhh.com, ahhhh.com, ahhhhh.com, ahhhhhh.com and so on..., all the way up to 62 'h's!

YouTube is a video-sharing platform which commenced operations on February 14, 2005 (Valentine's day). Three former PayPal employees -> Chad Hurley, Steve Chen and Jawed Karim created the YouTube service (as a dating app) until Google bought it in November 2006 for US$1.65 billion

Smoking near a Mac device - Len Academy

Smoking near an Apple (Mac) computer voids the warranty.

When you add /4 to the end of Facebook's URL, it will take you to Mark Zuckerberg.

You can try it on you own; or better still, try the link below:


Apple iPad retina - Len Academy

Apple iPad retina display is actually manufactured by Samsung

The big five tech companies of the world as at 2018 are :






Notable points in ICT

Python is one of the most popular programming languages, and will still remain relevant for a long time.

Python can be used for almost every kind of project including web application, machine learning, mobile and desktop applications, networking servers, APIs, scrapers, application’s backend and so on.

There is a great availability of third-party libraries for the python language. For this reason, it becomes one one of the easiest languages to learn as a beginner.

Believe it or not, Hypertext Preprocessor (PHP) still remains one of the most popular backend language for web applications, even though it is currently facing a stiff competition from python language.

Content Management Systems (CMS) like wordpress and drupal are written in PHP for its backend. Interestingly, some of facebook’s backend were also written in PHP.

As at 2019, the backend of more than 40% of active websites are powered with PHP. In fact, Len Academy is also powered by PHP for its backend.

If you wish to manipulate databases via Structured Query Language (SQL) with a programming language that has dynamic capabilities, then PHP is your language of choice.

Please read on the best programming languages to lean here

Below are notable dates on internet evolution:

  • 1983: The Domain Name System (DNS) created the '.com .edu .gov .org and .net' systems for naming websites

  • 1985: The first registered domain name - 'symbolics.com' came into existence

  • 1992: The first audio and video were uploaded over the internet

  • 1992: The phrase 'surfing the Internet' became popular

  • 1993: The number of websites reached 600

  • 1993: White House and United Nations go online

  • 1994: Microsoft creates a Web browser for Windows 95

  • 1994: Yahoo! is created by Jerry Yang and David Filo

  • 1995 Amazon and eBay were launched online

  • 1996: 'The Dancing Baby' becomes the first viral internet video

  • 1997: Netflix is founded by Reed Hastings and Marc Randolph

  • 1998: Google search engine came into existence

  • 2003: The worm 'SQL Slammer' spread over the internet within 10 minutes

  • 2004: Facebook goes online

Please read more notable dates on internet evolution here

Computer hardware is the collection of physical parts of a computer system.

Physical parts of a computer are those parts that you can see and touch. It may also be referred to as the 'equipment of the computer'.

When the computer case is opened (with a screwdriver), one would see the different hardware components inside of it. It's important to state that some other hardware components are present outside the computer case; and these are termed peripherals.

Below are hardware components seen inside the computer case:

  • Motherboard

  • Central Processing Unit (CPU)

  • Graphics Processing Unit (GPU)

  • Power supply Unit (PSU)

  • Northbridge

  • Southbridge

  • Peripheral Component Interconnect (PCI) slots

  • Network Interface Card (NIC)

  • Random Access Memory (RAM)

  • Ventilation fans

  • Heat sink

  • Hard Disc Drive (external present)
  • Solid State Drive (SSD)

  • CMOS battery

  • Optical Disc Drives (external present)

  • USB port, PS2 port, Ethernet port and other ports

  • Expansion Ports / Slots

Please read more on computer hardware here

Hardware components seen outside the computer case are called peripherals. The peripherals are grouped into the following:

  1. Input devices: They provide information to the computer.

  2. Output devices: Brings out information from the computer.

  3. Storage devices: They store information or data.

Below are examples of some peripherals:

  • Keyboard (input)

  • Monitor (output)

  • Mouse (input)

  • Webcam (input)

  • Touch Pad (input)

  • Universal Serial Bus (USB) flash drive or memory card (storage)

  • Hard disc drive (storage)

  • Stylus (input)

  • Joystick(input)

  • Printer (output)

  • Speaker (output)

  • Headphones (output)