OCR · GCSE · Computer Science
Course version: J277 · Version from Sept 2022
IP addressing and MAC addressing
Full specification wording
Wired and wireless networks, protocols and layers: IP addressing and MAC addressing
Every device needs an address to route data.
Checked against the OCR J277 specification on .
- Point 6 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Every device needs an address to route data. An IP address is a logical address, often assigned by a DHCP server, which can change when joining a new network. Routers use it to forward packets. IPv⁴ uses 32 bits (e.g. 192.168.1.10), but due to address exhaustion, IPv⁶ was created using 128 bits in hexadecimal. A MAC address is a physical address burned into the network interface card (NIC) by the manufacturer. It is fixed and used within a local network to identify the exact hardware.
What earns the marks
- An IP address is a logical address that can change when a device connects to a different network.
- IPv⁴ addresses are 32-bit and written as four decimal numbers separated by dots, for example 192.168.1.10.
- IPv⁶ addresses are 128-bit and written as eight groups of hexadecimal digits separated by colons.
- IPv⁶ was introduced because IPv⁴ addresses are running out, providing a much larger address space.
- A MAC address is a physical address set by the manufacturer and is normally fixed for the life of the network interface.
- MAC addresses are used within a local network to identify a specific network interface card when frames are delivered.
Common mistakes and how to put them right
Saying a MAC address changes when a device joins a new network.
Put it right: Link changeability to IP addresses and permanence to MAC addresses.
Confusing IPv⁴ and IPv⁶ formats.
Put it right: Memorise the bit length and format for both versions.
Believing a MAC address is assigned by the internet service provider.
Put it right: Name the manufacturer as the source of the MAC address.
Exam tips
- Use a packet journey example, such as a laptop sending a request to a web server, to show where each address is used.
- Learn one example of an IPv⁴ address and one example of an IPv⁶ address, and be ready to explain why IPv⁶ is needed.
Try the lesson
The start of the Wired and wireless networks, protocols and layers: IP addressing and MAC addressing lesson, made from checked teaching notes for this specification point.
Have a go first
Which type of address is assigned to a network interface by the manufacturer and is intended to stay the same for the life of the device?
Listen
Every device needs an address to route data. An IP address is a logical address, often assigned by a DHCP server, which can change when joining a new network. Routers use it to forward packets. IPv⁴ uses 32 bits (e.g. 192.168.1.10), but due to address exhaustion, IPv⁶ was created using 128 bits in hexadecimal. A MAC address is a physical address burned into the network interface card (NIC) by the manufacturer. It is fixed and used within a local network to identify the exact hardware. A strong answer earns marks for these points. An IP address is a logical address that can change when a device connects to a different network. IPv⁴ addresses are 32-bit and written as four decimal numbers separated by dots, for example 192.168.1.10. IPv⁶ addresses are 128-bit and written as eight groups of hexadecimal digits separated by colons. IPv⁶ was introduced because IPv⁴ addresses are running out, providing a much larger address space. A common slip: Saying a MAC address changes when a device joins a new network: it is the IP address that normally changes, while the MAC address stays with the hardware. Instead, link changeability to IP addresses and permanence to MAC addresses. Exam tip: Use a packet journey example, such as a laptop sending a request to a web server, to show where each address is used.
Key words
Say what each word means before you turn the card.
IP address
Try answering aloud or in your head before turning the card.
MAC address
Try answering aloud or in your head before turning the card.
IPv⁴
Try answering aloud or in your head before turning the card.
IPv⁶
Try answering aloud or in your head before turning the card.
See every definition
- IP address
- A logical address, often assigned by a DHCP server, which can change when a device joins a new network and which routers use to forward packets.
- MAC address
- A physical address burned into the network interface card by the manufacturer, fixed for the life of the interface and used within a local network to identify the exact hardware.
- IPv⁴
- A 32-bit address written as four decimal numbers separated by dots, for example 192.168.1.10.
- IPv⁶
- A 128-bit address written as eight groups of hexadecimal digits separated by colons, created because IPv⁴ addresses are running out.
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