IPv4 and IPv6 Addresses

Lesson plan

Level

Beginner

Time

About 60 minutes; the steps below add up to 59

A parcel passing through depots shows learners that one address stays the same while another changes at every stage, before IP and MAC addresses are named. Predictions then precede what two neighbouring addresses share, how 4.3 billion addresses can serve more devices, what a 169.254 address means and how to make addresses that never run out; checks follow the address comparison, the private ranges and the IPv6 shortening rules. The habit to build: read an address for what it tells you before acting on it.

Objectives

• Tell an IP address from a MAC address by what each does on a journey
• Describe an IPv4 address as 32 bits in four octets, with network and host portions
• Recognise private, public and special IPv4 ranges
• Read and shorten IPv6 addresses, and recognise the main kinds

Before the lesson

• Open this page on your own screen and use “Open the lesson window” to open the lesson in a second window. Share only that second window.
• Learners need the Number Systems and OSI Models lessons first.
• Have the three private ranges written up where they stay visible.
• The lesson takes about 59 minutes.
• In presentation mode every step is shown in turns: Next reveals one moment, part or answer at a time, and the instructor view names what is on screen and what comes next.

Steps

1. Introduction Opening

   On screen: the lesson’s title, module and number; Next adds its objectives and key terms, as the lesson page lists them; Next again begins the first step.

   Objectives on screen

   • Tell an IP address from a MAC address by what each does on a journey
   • Describe an IPv4 address as 32 bits in four octets, with network and host portions
   • Recognise private, public and special IPv4 ranges
   • Read and shorten IPv6 addresses, and recognise the main kinds

   Purpose: A parcel passing through depots shows learners that one address stays the same while another changes at every stage, before IP and MAC addresses are named. Predictions then precede what two neighbouring addresses share, how 4.3 billion addresses can serve more devices, what a 169.254 address means and how to make addresses that never run out; checks follow the address comparison, the private ranges and the IPv6 shortening rules. The habit to build: read an address for what it tells you before acting on it.

2. 1. Sending a parcel Think 5 min

   Purpose: Find the two kinds of address from a parcel’s journey.

   Ask

   • What stays the same on the parcel, and what changes?
   • What does a depot need to read?

   Responses to expect

   • The label and the next depot come quickly.
   • On screen in turns: the opening question, its answer; then the question on what the depot reads, and its answer.

   Discussion pause: Draw the journey with three depots before revealing the explanation.

   In the lesson window

   • Think it through: A parcel travels from Leeds to a house in Glasgow, passing through three depots on the way. What on the parcel stays the same for the whole journey, and what changes at each depot?
   • Think it through: What does a depot need to read to decide where to send the parcel next?

3. 2. IP addresses and MAC addresses Explain 9 min

   Purpose: Name IP and MAC addresses and compare them, with the limit of the comparison.

   Ask

   • Which address is replaced at every router?

   Responses to expect

   • Many think the IP address changes; point to the label.
   • On screen in turns: the opening; then the IP address as the label, and the MAC address as the next depot; the two addresses compared, with the MAC column held back; the MAC address column; the check question on three routers, and its answer; where the parcel comparison stops; where MAC addresses are taught.

   Discussion pause: The MAC column is held back: ask the class to fill it in from the parcel comparison before revealing.

   In the lesson window

   • Check your understanding: A packet crosses three routers on its way. Which of its two addresses is replaced at every router?

4. 3. The structure of an IPv4 address Predict 8 min

   Purpose: Show 32 bits in four octets, and the network and host portions.

   Ask

   • What do 192.168.1.10 and 192.168.1.77 share?

   Responses to expect

   • Most see the shared first three octets.
   • On screen in turns: the opening; then 192.168.1.10 as four octets; the question on two neighbouring addresses, and its answer; network and host portions; how the boundary is set.

   Misconceptions to challenge

   • A learner may believe: “The address itself shows which part is the network.” Respond: A separate setting, the mask or prefix, sets the boundary.

   In the lesson window

   • Think it through: Look at 192.168.1.10 and 192.168.1.77. What do the two addresses share, and what might that tell you?

5. 4. Public and private addresses Predict 11 min

   Purpose: Explain address reuse, the private ranges, and that not private is not always public.

   Ask

   • How could every device have an address?
   • Is 172.32.0.5 private?

   Responses to expect

   • The 172.16 to 172.31 boundary is the common trap.
   • On screen in turns: the opening question, its answer; then public and private addresses; a school as an example; the three private ranges; the check question on 172.32.0.5, and its answer; five addresses to check, starting with 10.200.3.4; 172.20.1.1; 172.40.1.1; 192.169.1.1; 198.51.100.7, and what it shows; IPv6’s equivalent of private addresses.

   Misconceptions to challenge

   • A learner may believe: “Any address that is not private is public.” Respond: Other special ranges exist.

   Discussion pause: Reveal the five addresses one at a time; let the class decide private or not before each answer.

   If the explanation does not land: Use phone extensions: every office can have an extension 201, but outside callers dial the office’s one public number.

   In the lesson window

   • Think it through: There are about 4.3 billion IPv4 addresses, but more devices than that. How could every device still have one?
   • Check your understanding: Using the table, is 172.32.0.5 a private address?

6. 5. Other special IPv4 addresses Predict 4 min

   Purpose: Recognise loopback, link-local, documentation addresses and 0.0.0.0.

   Ask

   • What has gone wrong for the 169.254 laptop?

   Responses to expect

   • Few know yet; accept “it did not get an address”.
   • On screen in turns: the opening question, its answer; then the other special ranges worth recognising.

   In the lesson window

   • Think it through: A laptop shows the address 169.254.12.7 and cannot reach anything, while its neighbours work normally. What might have gone wrong?

7. 6. IPv6 addresses Predict 11 min

   Purpose: Introduce IPv6, its notation and shortening rules, and its kinds of address.

   Ask

   • How would you make addresses that never run out?
   • Shorten the long address with both rules.

   Responses to expect

   • Using the double colon twice is the usual mistake.
   • On screen in turns: the opening question, its answer; then why IPv6 is 128 bits, and how it is written; two rules that shorten an IPv6 address; the check question on shortening an address, and its answer; expanding 2001:db8::10, starting with counting the groups; what the double colon replaces; restoring leading zeros; the address in full, and why :: appears once; the kinds of IPv6 address; why IPv6 has no broadcast; the address as an early clue.

   If the explanation does not land: Like a long phone number with repeated zeros: you may drop zeros at the start of each group, and shorten one long run of zero groups once, so the reader can still count what is missing.

   To go further

   • Why can the double colon appear only once? Try expanding an address that uses it twice.

   In the lesson window

   • Think it through: If you could redesign IP addresses so that they would never run out, what would you change?
   • Check your understanding: Apply both rules to 2001:0db8:0000:0000:0000:0000:0000:0001. Which is correct?

8. 7. Apply it in a new situation Apply 4 min

   Purpose: Set up independent application, ideally on a later day.

   Ask

   • Who will try these now, and who later in the week?

   Responses to expect

   • The odd laptop tests special ranges; the server claim tests what private means.
   • On screen in turns: the opening question, its answer; then the question on whether private means safe, and its answer.

   In the lesson window

   • Apply it: A user’s laptop shows 169.254.3.9, while colleagues’ laptops show addresses beginning 10.1.4. What does that suggest?
   • Apply it: A colleague says: “Our server has a private address, so it is safe from attack.” What is the best response?

9. 8. Check your understanding Check 4 min

   Purpose: Check the lesson against the approved revision-bank questions.

   Ask

   • Answer individually, then compare before revealing.

   Responses to expect

   • The address-widths question compares 32 and 128 bits.
   • On screen in turns: the opening; then the revision questions one at a time, each followed by its answer; where to practise next.

10. 9. What to remember Consolidate 3 min

    Purpose: Summarise the five points, the key terms and the misunderstandings.

    Ask

    • Without looking: name the three private IPv4 ranges.

    Responses to expect

    • 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16.
    • On screen in turns: the opening; then the summary; the key terms; the common misunderstandings.

11. Lesson recap Closing

    On screen: the lesson’s objectives again; Next adds the closing question, which asks the class to explain each one in their own words without looking back. It says nothing about what anyone has learnt: use the answers to decide what to revisit.

    Points to listen for

    • One address for the destination, one for the next step of the journey.
    • Four octets, split into network and host by a separate setting.
    • Private addresses are reused in every building and never routed on the internet.
    • Some ranges are neither private nor public: loopback, link-local, documentation.
    • IPv6 is longer, written in hex, and shortened by two rules.

Consolidation

• One address for the destination, one for the next step of the journey.
• Four octets, split into network and host by a separate setting.
• Private addresses are reused in every building and never routed on the internet.
• Some ranges are neither private nor public: loopback, link-local, documentation.
• IPv6 is longer, written in hex, and shortened by two rules.