IP Addresses (IPv4, IPv6), MAC Addresses & URLs

In this blog post, we are going to learn about the format of different addresses used on computer networks to uniquely identify hardware devices. We will investigate the use and format of:

• IPv4 Addresses,
• IPv6 Addresses,
• MAC Addresses.

IPv4 Addresses

An IP address is a unique identifier of a device on an IP network.

An IP address (IPv4) consists of 4 Bytes: 4 numbers between 0 and 255 separated by dots.

A dynamic IP Address can change every time your restart your device/reconnect to the network. Some devices can be configured on an IP network to have a static IP address: it will remain she same even if you restart your device.

As an IPv4 address consists of 4 Bytes (=32 bits), there are 2³² possible IP addresses which is just under 4.3 billions IP addresses. Though this seems like a large number, we are reaching a stage where we are running out of unique IP addresses. Remember, every device (router, computer, smartphone, smartwatch, smart TV, smart speaker, etc.) connected to the Internet will have its own IP address and there are nearly 8 billions human beings on planet Earth. This is the reason why the Internet is progressively upgrading to the next generation of IP addresses: IPv6…

IPv6 Addresses

To overcome the issue of the Internet running out of unique IPv4 addresses, a new format was introduced. IPv6 addresses consist of 16 Bytes (=128 bits). They are expressed in hexadecimal using 8 blocks of 2 Bytes (4 hexadecimal digits) separated by colons e.g.:

With 128 bits per IP address, we can generate 2¹²⁸ unique IP addresses. That’s 340,282,366,920,938,463,463,374,607,431,768,211,456 IP addresses, more than enough to give each grain of sand on planet Earth a unique IP address!!!

MAC Addresses

A MAC address consists of 6 Bytes of Data, expressed in hexadecimal, separated using colons. e.g.

A MAC Address is static and unique for a device. It cannot change. It is hardcoded into the device by the manufacturer when the device is built. (A bit like the chassis number of a car!)

Networking equipment such as routers and switches use IP addresses and/or MAC addresses to direct traffic between computers/devices on the network.

URL: Uniform Resource Locator

A live website is hosted/stored on a webserver and consists of different files such as HTML pages, png graphics, jpg pictures, gif animations and other multimedia files (mp3 audio clips, mp4 movie clips, pdf documents etc.). These files are stored on the web server within a root folder and other subfolders. A URL is used to request a specific file (resource) stored on a web server.

A URL is used to request/locate a specific resource stored on a web server. It consists of:

• The protocol used to access the web page: either HTTP or HTTPs,
• The Domain Name to identify the web server,
• Optional: Folder/Sub-folder structure: If the resource/file you are trying to access is not on the root folder of the website but in a sub-folder,
• Optional: File name: the file name and extension of the file you are requesting. If the filename is not provided, the server will return the index.html file if it exists.

Error 404: Page Not Found

When a URL points towards a file that cannot be located or simply does not exist on the webserver, a 404 error message is returned to the web browser!

Domain Name Server

In order to connect to a website, your web-browser needs to know the IP address of the webserver where the website is hosted. However, IP address are tricky to remember (for human beings). This is why domain names were invented! Domains names such as 101computing.net or amazon.com are easy to remember. When the user types a domain name in the address bar of the browser, the browser automatically contacts a DNS server on the Internet. The DNS server will then lookup for the matching IP address for this domain name and return it to the web-browser. The web-browser will then be able to contact the webserver to request a specific page:

In a way, we could say that a Domain Name Server is the equivalent of of the phone book that we used to consult when we had the name of someone we wanted to call but did not know their actual phone number. We would lookup for their name in the phone book to retrieve their phone number. Similarly, a Domain Name Server is used to lookup a domain name to find its IP address!

Python Task #1

Write a python program to generate and output:

• A random IPv4 address,
• A random IPv6 address,
• A random MAC address.

Python Task #2

Write a python program that asks the user to enter a URL. The program will then extract and output the following components of the URL:

• Protocol,
• Domain Name,
• Folder Structure,
• File name.

Solution...

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