Q.(a) Differentiate between wired and wireless transmission.

Wired Media Categories – A First Look

Think about the last time you plugged a charging cable into your phone, or connected your laptop to a router with an Ethernet cable. That physical wire—the thing you can touch and see—is what we call wired media. In the world of computer networks, "media" simply means the physical path through which data travels from one device to another. Wired media, then, is any communication channel that uses a solid conductor (like copper or glass) to carry signals.

The key idea is simple: instead of sending data through the air (like Wi-Fi or Bluetooth), wired media sends it along a physical cable. This matters because wires offer reliability, speed, and security that wireless connections often cannot match. For a commerce or humanities student, understanding this helps you grasp why businesses, banks, and government offices still rely heavily on cables—even in an age of wireless everything.

The Three Main Categories

The NCERT textbook (Class 12, Computer Science, Chapter: Communication and Network Concepts) classifies wired media into three types. Each works differently and suits different situations.

1. Twisted Pair Cable

Imagine two copper wires twisted around each other like a DNA helix. That is the basic structure. The twisting cancels out electromagnetic interference from nearby wires or devices, keeping the signal clean.

• Unshielded Twisted Pair (UTP): The most common type. You see it in telephone lines and home Ethernet cables. It is cheap, flexible, and easy to install.
• Shielded Twisted Pair (STP): Has an extra metal foil or braid around the twisted pairs. This blocks more interference, so it is used in industrial areas or places with lots of electrical noise.

2. Coaxial Cable

This is the thick, round cable you might have seen connecting a TV to a cable box or a satellite dish. It has a central copper wire, surrounded by a plastic insulator, then a braided metal shield, and finally an outer plastic jacket.

The design makes coaxial cable much better at resisting interference than twisted pair. It can carry signals over longer distances—up to a few hundred metres—without losing quality.

• Used for cable television, internet connections (cable broadband), and older Ethernet networks.
• More expensive and less flexible than twisted pair, but more durable.

3. Optical Fibre Cable

This is the most advanced wired medium. Instead of copper, it uses thin strands of glass or plastic. Data travels as pulses of light, not electricity. A laser or LED sends light down the fibre, and the light bounces off the inner walls (total internal reflection) to reach the other end.

• Extremely high speed: Light travels faster than electrical signals in copper.
• Very long distances: Signals can go kilometres without needing a booster.
• Immune to interference: No electromagnetic noise affects light. …

Imagine you want to visit a friend who lives in a huge city. You don't know their exact street address, but you do know their name. So you pull out a phone book or a digital directory, look up the name, and find the address. That is exactly what the Domain Name System does for the internet, but at a scale and speed that is almost magical.

The internet is a network of computers, and every computer or website is identified by a string of numbers called an IP address (like 192.0.2.1). Humans are terrible at remembering long strings of numbers. We are much better at remembering words, like "google.com" or "facebook.com." The Domain Name System, or DNS, is the phonebook of the internet. It translates the human-friendly domain names you type into a browser into the machine-friendly IP addresses that computers use to find each other.

When you type a website address into your browser, your computer doesn't know where to go. It first asks a DNS resolver—think of it as a helpful librarian. This librarian checks its own memory, and if it doesn't know the answer, it goes on a quick, systematic search. It asks the root server (the master index), then the top-level domain server (like the one for ".com" or ".org"), and finally the authoritative name server for that specific domain. That last server holds the exact IP address. The librarian brings that address back to your computer, and your browser can then connect and load the website. All of this happens in a fraction of a second.