Learning Objectives
By the end of this lesson, you will be able to:
- Understand that a computer needs aNetwork Interface Card (NIC)to access a network
- Understand what is meant by and the purpose of aMedia Access Control (MAC) address, including its structure
- Understand what is meant by and the purpose of anInternet Protocol (IP) address
- Understand that there are different types of IP address —IPv4andIPv6,staticanddynamic,publicandprivate
- Describe the role of arouterin a network
Key Terms
Network Interface Card (NIC)
Hardware that allows a device to connect to a wired or wireless network. Contains a MAC address.
MAC Address
Media Access Control address — a unique 48-bit identifier given to a NIC at manufacture. Used to route frames on a LAN.
IP Address
Internet Protocol address — a unique identifier given to a device that communicates over the internet (WAN).
IPv4
32-bit IP address written as four denary numbers (0–255) separated by dots (e.g. 192.168.1.1).
IPv6
128-bit IP address written as eight groups of four hexadecimal digits separated by colons.
Static IP Address
An IP address that does not change. Used for servers and websites so they can always be found at the same address.
Dynamic IP Address
An IP address that can change each time a device connects. Assigned automatically by a DHCP server.
Public IP Address
Unique IP address assigned to a network router by an ISP. Can be accessed directly over the internet.
Private IP Address
Unique IP address assigned by a router to devices on its local network. More secure than a public address.
Router
A device that sends data between networks, connects a LAN to the internet, and assigns IP addresses.
DHCP
Dynamic Host Configuration Protocol — automatically assigns dynamic IP addresses to devices on a network.
WAN
Wide Area Network — a network that covers a large geographical area, such as the internet.
LAN
Local Area Network — a network that covers a small geographical area, such as a school or office.
UAA (Universally Administered MAC Address)
The most common type of MAC address — set by the manufacturer at the factory.
LAA (Locally Administered MAC Address)
A MAC address that has been changed by the user or organisation. Rare.
ISP
Internet Service Provider — a company that provides access to the internet.
1. Network Interface Card (NIC)
ANetwork Interface Card (NIC)is required for a computer to connect to a network. It allows a device to connect to either awiredorwirelessnetwork and enables your computer to send and receive data over a network.
Key Facts about NICs
- A NIC uses a set of rules (protocol) to determine how the connection should work.
- Every device connecting to a network needs a NIC.
- NICs are also referred to asnetwork interface controllersornetwork adapters.
- Early NICs were expansion cards plugged into a slot in the motherboard.
- Today, NICs are built directly into the motherboard due to low cost and the universal nature of Ethernet.
- A NIC contains aMAC address, generated at the manufacturing stage.
- A device can have multiple separate connections to a network via NICs — each connection has its own unique MAC address.
Wired vs Wireless NICs
Wired NIC
Connects a device to a wired network using an Ethernet cable. Usually built into the motherboard.
Wireless NIC (WNIC)
Allows a device to connect without cables using wireless connectivity (microwaves). Can be integrated into the device or plugged in (e.g. a USB dongle).
Example: Viewing NICs and MAC addresses in Windows
Open Command Prompt and type:ipconfig /all
This displays the Physical Address (MAC address) for each network adapter.
Device
NIC
MAC Address
Activity 1: Network Interface Cards
- State the purpose of a Network Interface Card (NIC). [2]
- Give two types of NIC and explain the difference between them. [2]
- What does a NIC contain that is generated at the manufacturing stage? [1]
Solution:
- A NIC connects a device to a wired or wireless network [1]. It allows the device to send and receive data over a network [1].
- Wired NIC and wireless NIC (WNIC) [1]. A wired NIC uses a cable (Ethernet) while a wireless NIC uses wireless connectivity (microwaves) [1].
- A Media Access Control (MAC) address [1]
Check Your Understanding: NIC
1. What is a Network Interface Card (NIC)? [2 marks]
- [1]Hardware that allows a device to connect to a network
- [1]It enables the device to send and receive data over a wired or wireless network
2. What is a wireless NIC (WNIC) and how is it different from a wired NIC? [2 marks]
- [1]A WNIC allows a device to connect to a network without cables, using wireless connectivity (microwaves)
- [1]A wired NIC uses a cable (Ethernet) to connect to the network
3. What is stored on a NIC that is generated at the manufacturing stage? [1 mark]
- [1]A Media Access Control (MAC) address
4. What is a standalone device? [1 mark]
- [1]A computing device that is physically unable to communicate with any other device
5. How has the implementation of NICs changed over time? [2 marks]
- [1]Early NICs were expansion cards plugged into a slot on the motherboard
- [1]Today, NICs are built directly into the motherboard
6. Why does a device need a NIC to access a network? [2 marks]
- [1]The NIC provides the physical connection (wired or wireless) to the network
- [1]It contains the MAC address needed to identify the device on the network
2. Media Access Control (MAC) Address
AMAC (Media Access Control) addressis a unique identifier given to devices which communicate over alocal area network (LAN). A NIC is given a MAC address at the point of manufacture.
Key Facts about MAC Addresses
- MAC addresses arestatic— they never change.
- They are used to routeframeson alocal area network (LAN).
- Each MAC address isuniqueto every NIC.
- A MAC address is48 bitsin length.
- MAC addresses are represented assix groups of hexadecimal digits(e.g. 00:0a:95:9d:68:16).
- The first three pairs (first 6 hex digits / 3 bytes) are themanufacturer ID number (OUI).
- The last three pairs (last 6 hex digits / 3 bytes) are theserial numberof the NIC.
- If the NIC is replaced, the MAC address will also change.
- There are enough unique MAC addresses for roughly 281 trillion devices.
Structure of a MAC Address
2A
B3
19
F6
82
CD
Manufacturer Code
(3 bytes / 6 hex digits)Serial Number
(3 bytes / 6 hex digits)
(3 bytes / 6 hex digits)Serial Number
(3 bytes / 6 hex digits)
Example MAC Address
00 - 1C - B3 - 4F - 25 - FF
Manufacturer: 001CB3 (Apple Corporation)
Serial Number: 4F25FF
Types of MAC Address
| Type | Description |
|---|---|
| Universally Administered MAC Address (UAA) | By far the most common type of MAC address. Set by the manufacturer at the factory. |
| Locally Administered MAC Address (LAA) | Rare — a MAC address that has been changed by the user or organisation. Causes problems if the changed address is not unique. |
Why Might a MAC Address Need to be Changed?
- Certain software used on mainframe systems needs all MAC addresses to fall into a strict format.
- It may be necessary to bypass a MAC address filter on a router or firewall.
- To get past certain types of network restrictions, it may be necessary to emulate unrestricted MAC addresses.
Interactive MAC Address Viewer
Enter a MAC address to see its structure broken down into manufacturer code and serial number.
Activity 2: MAC Addresses
- Explain what is meant by a MAC address. [4]
- Describe the structure of a MAC address. [3]
- Give two reasons why a user might change a MAC address. [2]
Solution:
- Media Access Control address [1]. Used to identify a device on a network [1]. It is a unique address [1]. It is a static address / it does not change / it is set by the manufacturer [1].
- 48 bits in length [1]. Represented as six groups of hexadecimal digits [1]. The first three pairs are the manufacturer ID; the last three pairs are the serial number [1].
- Any two from: to bypass a MAC address filter on a router or firewall [1]; to emulate unrestricted MAC addresses to get past network restrictions [1]; certain software requires MAC addresses to fall into a strict format [1].
Check Your Understanding: MAC Address
1. What does MAC stand for? [1 mark]
- [1]Media Access Control
2. How many bits are in a MAC address? [1 mark]
- [1]48 bits
3. What does the first half of a MAC address represent? [1 mark]
- [1]The manufacturer code / unique manufacturer ID
4. Is a MAC address static or dynamic? Explain. [2 marks]
- [1]Static
- [1]It never changes / it is set by the manufacturer at the point of manufacture
5. What happens to the MAC address if the NIC is replaced? [1 mark]
- [1]The MAC address will change (the new NIC has its own unique MAC address)
6. What is the difference between UAA and LAA? [2 marks]
- [1]UAA (Universally Administered MAC Address) is set by the manufacturer at the factory and is the most common type
- [1]LAA (Locally Administered MAC Address) has been changed by the user or organisation — it is rare
3. Internet Protocol (IP) Addresses
AnIP (Internet Protocol) addressis a unique identifier given to devices which communicate over theInternet (WAN). IP addresses make it possible to deliver data to the right device. A device connecting to a network will be given an IP address — if it moves to a different network, the IP address will change.
Key Facts about IP Addresses
- IP addresses are used to routepacketson awide area network (WAN).
- IP addresses can bestatic(they do not change) ordynamic(they can change).
- Static IP addressesare commonly used for servers and websites so they can always be found at the same address.
- Dynamic IP addressesare assigned automatically by aDHCP server(Dynamic Host Configuration Protocol).
- There are two versions of IP in use:IPv4andIPv6.
Public vs Private IP Addresses
| Public IP Address | Private IP Address |
|---|---|
| Unique IP address assigned to your network router by your ISP | Unique address assigned by your network router to your device |
| Can be accessed directly over the internet | Used within a local network only |
| Less secure than a private address | More secure |
| Unique within the internet | Unique within the local network — can be duplicated within other networks |
IPv4
- 32 bits (4 bytes)in size.
- Represented asfour blocks of denary numbersbetween 0 and 255, separated by full stops.
- Each block is one byte (8 bits).
- Example:193.74.211.63
- Provides approximately4 billionpossible addresses (2³²).
- An IPv4 address has two parts:Network identifierandHost identifier.
- IPv4 is being replaced by IPv6 because unique static addresses are running out.
193
74
211
63
Network identifier (3 bytes)Host identifier (1 byte)
IPv6
- 128 bits (16 bytes)in size.
- Represented aseight groups of four hexadecimal digits, separated by colons.
- Each group is 16 bits (2 bytes).
- Example:2001:0db8:85a3:0000:0000:8a2e:0370:7334
- Could provide overone billion unique addresses for every person on the planet(2¹²⁸ — approximately 340 trillion-trillion-trillion combinations).
- Advantages of IPv6 over IPv4:Removes risk of IP address collisions, has built-in authentication checks, allows for more efficient packet routes.
2001
0db8
85a3
0000
0000
8a2e
0370
7334
Static vs Dynamic IP Addresses
| Static IP Address | Dynamic IP Address |
|---|---|
| Permanently assigned to a device by an ISP; does not change | Assigned automatically by a router/DHCP server; can change periodically |
| Allows each device to be fully traceable | Greater privacy since they change each time a user logs on |
| More cost-effective for ISPs as they can reuse unused IP addresses | Less secure — more difficult to track who is accessing the network |
| Assigned to: remote servers hosting a website, online databases, FTP servers | Assigned to: typical home devices, mobile devices connecting to public Wi-Fi |
MAC Address vs IP Address
| MAC Address | IP Address |
|---|---|
| Identifies the physical address of a device on a network | Identifies the global address on the internet |
| Unique for a device on the network | May not necessarily be unique |
| Assigned by the manufacturer of the device — part of the NIC | Dynamic IP addresses are assigned by ISP using DHCP |
| Can be universal or local | Dynamic IP addresses change; static IP addresses do not |
| Used to identify the sender's and recipient's devices when a packet is sent/received | Used in routing operations as they identify where the device is connected to the internet |
| Uses 48 bits | Uses 32 bits (IPv4) or 128 bits (IPv6) |
| Can be UAA or LAA | Can be static or dynamic |
Real-Life Analogy: House and People
TheIP addresscan be thought of as the address of the house you live in (it uniquely identifies the location). TheMAC addresscan be thought of as a way of uniquely identifying each person living in that house. It is possible to move house (so your IP address will change) but the same people will be living in the new house (so their MAC addresses will remain unchanged).
Interactive IP Address Explorer
Explore IPv4 and IPv6 address formats and see how they differ.
Activity 3: IP Addresses
- Describe two differences between an IP address and a MAC address. [2]
- Explain the difference between IPv4 and IPv6. [4]
- Explain the difference between a static and a dynamic IP address. [2]
Solution:
- IP address is dynamic / can change; MAC address is static / cannot change [1]. IP address is used to communicate on a WAN/Internet; MAC address is used to communicate on a LAN [1].
- IPv4 uses 32 bits; IPv6 uses 128 bits [1]. IPv4 is written as four denary numbers separated by dots; IPv6 is written as eight groups of four hexadecimal digits separated by colons [1]. IPv4 provides about 4 billion addresses; IPv6 provides a vastly larger number [1]. IPv4 is being replaced by IPv6 because addresses are running out [1].
- A static IP address does not change; a dynamic IP address can change each time a device connects [1]. Static addresses are used for servers/websites; dynamic addresses are assigned by a DHCP server [1].
Check Your Understanding: IP Addresses
1. What is an IP address? [2 marks]
- [1]A unique identifier given to devices that communicate over the internet (WAN)
- [1]Used to route packets to the correct device
2. How many bits are in an IPv4 address? [1 mark]
- [1]32 bits (4 bytes)
3. How many bits are in an IPv6 address? [1 mark]
- [1]128 bits (16 bytes)
4. What is a dynamic IP address and how is it assigned? [2 marks]
- [1]An IP address that can change each time a device connects
- [1]It is assigned automatically by a DHCP server / router
5. What is the difference between a public and a private IP address? [2 marks]
- [1]A public IP address is assigned to a network router by an ISP and can be accessed directly over the internet
- [1]A private IP address is assigned by a router to devices on its local network and is more secure
6. Why is IPv4 being replaced by IPv6? [2 marks]
- [1]Unique static IPv4 addresses are running out (only about 4 billion available)
- [1]IPv6 provides a vastly larger number of addresses (2¹²⁸)
4. The Role of a Router
Arouteris responsible for routing data packets between different networks. It connects networks together — local area networks (LANs) to the wider internet which is a type of wide area network (WAN).
Role of a Router
- Sends and receives packets of data.
- Connects a local network to the internet (LAN to WAN).
- Assigns IP addresses to nodes/devices on the network.
- Converts packets from one protocol to another.
- Directs traffic (packets) from one router to another using IP addresses.
- Receives inbound data and directs it to a specific device on a network (LAN).
- Manages and prioritises data traffic to help keep connections stable.
Typical Router Connections
- A cable connecting it to the internet (via the ISP).
- Several other cables connecting to computers and other devices on the LAN.
- Wireless connectivity (Wi-Fi) for devices without cables.
How a Router Transmits Data Packets
- Router inspects the data packet sent from a computer.
- Router checks the IP address in the packet header.
- Router sends the packet to the appropriate switch.
- The data is delivered to the correct device using the MAC destination address.
- If the MAC address doesn't match any device on that switch, the packet is passed to another switch on the same network until the appropriate device is found.
Device A
192.168.0.2
Router
192.168.0.1
Internet
82.43.245.37
Router vs Modem
Amodemconverts signals from your ISP into a form your network can use. Arouterdirects traffic between your local network and the internet, and between devices on your local network. Many home devices combine both functions into one box.
Activity 4: Routers
- Describe the role of a router in a network. [4]
- Draw and annotate a diagram to represent the role of a router. [4]
Solution:
- Any four from: sends and receives packets of data [1]; connects a local network to the internet [1]; assigns IP addresses to devices [1]; converts packets from one protocol to another [1]; directs traffic using IP addresses [1].
- Diagram should show: a packet with an IP address [1]; a router examining the packet header for the IP address of the destination [1]; an arrow to a destination device [1]; a label saying "packet sent to correct destination using fastest route" [1].
Check Your Understanding: Routers
1. What is the main role of a router? [2 marks]
- [1]To route data packets between different networks
- [1]To connect a local area network (LAN) to a wide area network (WAN) / the internet
2. How does a router know where to send a data packet? [2 marks]
- [1]It examines the packet header
- [1]It reads the IP address of the destination and uses this to route the packet
3. What else can a router do besides routing data? [2 marks]
- [1]Assign IP addresses to devices on the network
- [1]Convert packets from one protocol to another / manage and prioritise data traffic
4. What is the difference between a router and a modem? [2 marks]
- [1]A modem converts signals from the ISP into a form the network can use
- [1]A router directs traffic between networks and between devices on a local network
5. What connections would you typically find on a home router? [3 marks]
- [1]A cable connecting it to the internet (via the ISP)
- [1]Several cables connecting to computers and other devices on the LAN
- [1]Wireless connectivity (Wi-Fi) for devices without cables
6. Why does a router have both a WAN-facing and a LAN-facing IP address? [2 marks]
- [1]The WAN-facing IP address allows the router to communicate over the internet
- [1]The LAN-facing IP address enables devices on the local network to communicate with the router and with each other / allows a LAN device to have the same IP address as another device on a separate LAN
Key Takeaways
- ANetwork Interface Card (NIC)is required for a device to connect to a wired or wireless network.
- A NIC contains aMAC address, generated at the manufacturing stage.
- AMAC addressis a unique 48-bit identifier, written as six groups of hexadecimal digits.
- The first half of a MAC address is themanufacturer code; the second half is theserial number.
- MAC addresses arestatic— they never change. If the NIC is replaced, the MAC address changes.
- MAC addresses are used to routeframeson aLAN.
- AnIP addressis a unique identifier for a device on aWAN/Internet.
- IPv4uses 32 bits, written as four denary numbers separated by dots.
- IPv6uses 128 bits, written as eight groups of four hexadecimal digits separated by colons.
- Static IP addressesdo not change — used for servers and websites.
- Dynamic IP addressescan change — assigned automatically by a DHCP server.
- Public IP addressesare assigned by an ISP and are accessible over the internet.
- Private IP addressesare assigned by a router to devices on a local network and are more secure.
- IP addresses are used to routepacketson aWAN.
- Aroutersends data between networks, connects a LAN to the internet, and assigns IP addresses.
- Routers examine the packet header to find the destination IP address and route the packet accordingly.
Question Bank
1. Describe what is meant by a MAC address. [4 marks]
- [1]Media Access Control (address)
- [1]Used to identify a device on a network
- [1]It is a unique address / it is a static address that does not change
- [1]It is set by the manufacturer; the first part is the manufacturer ID and the second part is the serial number
2. Describe two differences between IP addresses and MAC addresses. [2 marks]
- [1]IP address is dynamic/can change; MAC address is static/cannot change
- [1]IP address is used to communicate on a WAN/Internet; MAC address is used to communicate on a LAN
3. Four statements are given about MAC addresses and IP addresses. Tick to show whether each statement is True or False. [4 marks]
- A MAC address is unique to a computer on a network →True
- Once an IP address has been set it cannot be changed →False
- A MAC address is made up of the computer's serial number and the IP address →False
- If a computer does not have an IP address it cannot communicate with another device using the Internet →True
4. Explain how a router transmits a data packet to the correct device. [4 marks]
- [1]Router examines the data packet
- [1]It looks at the header which contains the IP address of the destination
- [1]It sends the packet to the appropriate switch
- [1]The data is delivered to the correct device using the MAC destination address / if MAC doesn't match, it passes to another switch until the device is found
5. Explain what is meant by an IP address. [3 marks]
- [1]Internet Protocol address
- [1]A unique identifier given to devices that communicate over the internet (WAN)
- [1]It can be static (doesn't change) or dynamic (can change)
6. Explain the difference between IPv4 and IPv6 addresses. [4 marks]
- [1]IPv4 uses 32 bits; IPv6 uses 128 bits
- [1]IPv4 is written as four denary numbers separated by dots; IPv6 is written as eight groups of four hexadecimal digits separated by colons
- [1]IPv4 provides about 4 billion addresses; IPv6 provides a vastly larger number
- [1]IPv4 is being replaced by IPv6 because unique static addresses are running out
7. Describe the role of an Internet Service Provider (ISP). [6 marks]
- [1]Provide access to the internet (dial-up/broadband)
- [1]Usually charge a monthly fee
- [1]Monitor usage
- [1]Give users an IP address
- [1]Determine bandwidth
- [1]Support domain names / provide security services / provide web hosting / provide email
8. What is a NIC and why is it needed? [3 marks]
- [1]Network Interface Card
- [1]Allows a device to connect to a wired or wireless network
- [1]Contains the MAC address needed to identify the device on the network
9. The table shows four definitions. Complete the table giving the missing Term for each definition. [4 marks]
- A data transmission method that sends data one bit at a time, down a single wire →Serial
- An address given to a device on a network. The address is assigned by the network →IP (address)
- The software used to render HTML and display a web page →Browser
- An address given to a device at the manufacturing stage that can be used to identify the device on a network →MAC (address)
10. Give two other examples where hexadecimal can be used. [2 marks]
- [1]Colour codes / colour in HTML or CSS
- [1]Error messages / locations in memory / memory dump / debugging / IP address / ASCII / Unicode / assembly language / URL