Ch 4 · 3.4 Network Hardware · IGCSE Computer Science 0478
Topic 4 of 4 in Hardware — IGCSE Computer Science 0478 — 49 lessons.
Introduction
For a computer to join a network, it needs the right hardware and two kinds of address: one built into the hardware and one given by the network. (Syllabus section 3.4.)
Key ideas — Network interface card (NIC)
A computer needs a network interface card (NIC) to connect to and access a network (wired or wireless). The NIC is given a unique MAC address when it is manufactured.
🧑🏫 Teacher's explanation
Think of a network like a massive international postal system. If you want to send a letter, your house needs a physical mailbox (the NIC) to receive it. Even if you have a mailbox, the postman needs to know your specific, permanent house number (the MAC address) to find you, but they also need to know your temporary, changing location in the city's routing system (the IP address) to get the letter to your neighborhood (the Router).
📖 Definitions
🔍 Worked example — Easy
A NIC has a manufacturer code of 00:1A:2B and a serial code of 3C:4D:5E. Express the full MAC address in hexadecimal.
🔍 Worked example — Standard
Compare IPv4 and IPv6 in terms of address space size and format.
🔍 Worked example — Exam-style
A router is assigned a dynamic IP address. What is the primary difference between this and a static IP address?
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) Identify the hardware component required for the computer to communicate on the network. [1] (b) Explain the difference between the MAC address and the IP address of the computer. [3] [4 marks]
Key ideas — MAC address
A media access control (MAC) address uniquely identifies a device (its NIC) on a network.
🧑🏫 Teacher's explanation
Imagine you are in a massive international airport. Every person has a unique passport number that never changes, no matter which country they visit. This passport number is like a MAC address. Even if you move from London to New York (changing your 'IP address' or location), your passport number stays exactly the same because it identifies *who* you are, not *where* you are.
📖 Definitions
🔍 Worked example — Easy
A NIC has a MAC address represented by the following 48 bits: 00000000 00001111 00110011 01010101 01100110 01110111. Convert the first 8 bits into a hexadecimal pair.
🔍 Worked example — Standard
A MAC address is A1:B2:C3:D4:E5:F6. Identify the manufacturer code and the serial code.
🔍 Worked example — Exam-style
A device has a MAC address where the manufacturer code is 00:50:56 and the serial code is 00:01:02. Write the full MAC address in standard hexadecimal format.
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) State the purpose of the MAC address stored on the NIC. [1] (b) Describe how a MAC address is structured. [3] [4 marks]
Key ideas — IP address
An internet protocol (IP) address identifies a device on a network or the internet, so data can be sent to the right place. It is allocated by the network (e.g. by the router), unlike a MAC address.
🧑🏫 Teacher's explanation
Imagine you are sending a letter through the postal service. The MAC address is like your social security number or your fingerprint; it is unique to you and never changes, no matter where you move. However, the IP address is like your current mailing address. If you move to a new house, your mailing address changes so the postman knows where to find you.
📖 Definitions
🔍 Worked example — Easy
Convert the IPv4 octet 192 into an 8-bit binary number.
🔍 Worked example — Standard
A web server requires a consistent address so that users can always find it. Should it be assigned a static or dynamic IP address? Explain why.
🔍 Worked example — Exam-style
Calculate the total number of possible addresses available in IPv4 compared to IPv6 using powers of 2.
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) State which type of IP address (static or dynamic) should be assigned to the web server. [1] (b) Explain why the employees' computers should be assigned dynamic IP addresses instead of static ones. [2] [3 marks]
Key ideas — The router
A router:
🧑🏫 Teacher's explanation
Imagine you are sending a letter through the postal service. The envelope has a unique ID for the specific house (the MAC address) and a routing instruction for the city and street (the IP address). If you just drop the letter in a mailbox, it might get lost. You need a post office worker to look at the address and decide which truck or plane it needs to go on to reach the next destination.
📖 Definitions
🔍 Worked example — Easy
A MAC address consists of a manufacturer code and a serial code. If the manufacturer code is A1:B2:C3 and the serial code is 45:67:89, what is the full MAC address?
🔍 Worked example — Standard
Identify the difference between a static IP address and a dynamic IP address.
🔍 Worked example — Exam-style
Compare IPv4 and IPv6 in terms of address space and format.
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) State the purpose of the Network Interface Card (NIC) in each computer. [1] (b) Explain the role of the router in this network. [2] [3 marks]
Worked example
A MAC address is assigned to the device's NIC by the manufacturer and is normally fixed; it identifies the physical device. An IP address is allocated by the network when the device connects, can be static or dynamic, and identifies the device's location on the network or internet so that data can be routed to it.
🔍 Worked example — Easy
Identify the component and the method of assignment for the following: 'A unique identifier assigned to a device by the manufacturer at the point of manufacture.'
🔍 Worked example — Standard
A device is connected to a network. It is assigned the address 192.168.1.15. Is this address static or dynamic, and what is its primary purpose?
🔍 Worked example — Exam-style
Compare IPv4 and IPv6 in terms of address space and format.
⚠️ Common errors
Common mistakes
Practice
Answers: (1) To connect to and access a network. (2) 48 bits written as 12 hexadecimal digits; first half the manufacturer code, second half the serial code. (3) IPv4 is 32 bits, written as four denary numbers; IPv6 is 128 bits, written as eight groups of hex digits; IPv6 has far more addresses. (4) So that it can always be found at the same address. (5) Any two: forwards data to its destination; assigns IP addresses; connects a local network to the internet.