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Storage Devices and Network Hardware: Question 4

Syllabus 3.4

Structured 7 marks

A family's home network has one router, provided by their internet service provider. A laptop and a smart TV are both connected to this router by network cable, and each device has its own network interface card (NIC) fitted inside it.

(a) State the type of address given to each device's NIC at the moment it is manufactured, and state the number system in which this address is usually written. [2]

(b) The router currently gives the laptop the IP address 192.168.1.5. Next month, the router might give the laptop a completely different IP address instead. Explain why the laptop's IP address is able to change like this, when the address from part (a) never changes. [2]

(c) Give three separate ways in which the router controls how the laptop and the smart TV are able to reach websites on the internet. [3]

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Worked solution

Part (a): The address fixed at manufacture

Every NIC is given a media access control (MAC) address at the moment it is manufactured. This address is usually written in hexadecimal, and it is created from the manufacturer’s own code combined with a serial code specific to that NIC, which is why it is unique to that piece of hardware.

Part (b): Why the IP address can change but the MAC address cannot

The address in part (a), the MAC address, is fixed permanently into the NIC at manufacture, so it is the same for as long as that NIC exists, no matter which network the laptop joins. An IP address, however, is not fixed to the hardware. It is allocated by the network the device is connected to (here, by the family’s router), and it can be static (fixed by choice) or dynamic (reassigned automatically). Because the router is responsible for allocating the laptop’s IP address, it is able to give the laptop a different IP address next month, even though the laptop’s underlying MAC address has not changed at all.

Part (c): Three separate roles of the router

The router plays several distinct roles that let the laptop and the smart TV reach websites on the internet:

  1. It sends data to a specific destination on the network, directing traffic to and from the correct device.
  2. It can assign IP addresses to devices on the network, such as giving the laptop and the smart TV each their own IP address.
  3. It can connect the local (home) network to the internet, providing the link the laptop and smart TV need to reach websites outside the home network.

Each of these is a genuinely separate function of the router, rather than three ways of describing the same thing.

Final answers

  • (a) MAC address, usually written in hexadecimal.
  • (b) The MAC address is fixed at manufacture and never changes; the IP address is allocated by the network and can be static or dynamic, so the router can reassign it.
  • (c) Any three of: sends data to a specific destination; can assign IP addresses; can connect the local network to the internet.