Inspecting Network Configuration: Windows, Linux and VyOS

Lesson plan

Level

Beginner

Time

About 50 minutes; the steps below add up to 49

Learners list, from the whole module, the settings they would look at on a laptop that reaches nothing, and say why to look before changing anything, so the settings table confirms their list. Predictions then precede whether the Windows excerpt makes sense, which Linux labels hold which values and why “what is this machine’s IP address?” can be the wrong question; checks follow a gateway on the wrong network and the up-and-running flags. The habit to build: read, judge against the earlier lessons, and report; change nothing without authority.

Objectives

• Name the settings that explain most connection problems
• Read ipconfig /all on Windows and judge whether the configuration makes sense
• Read ip addr show and ip -4 route on Linux, and a VyOS routing table
• Use ifconfig to find which interface is on the network you care about

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 Subnetting, DHCP and ARP and IP forwarding lessons first.
• All the command output in the lesson is illustrative; if you show live output, use a machine you control and keep it to viewing commands.
• The lesson takes about 49 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

   • Name the settings that explain most connection problems
   • Read ipconfig /all on Windows and judge whether the configuration makes sense
   • Read ip addr show and ip -4 route on Linux, and a VyOS routing table
   • Use ifconfig to find which interface is on the network you care about

   Purpose: Learners list, from the whole module, the settings they would look at on a laptop that reaches nothing, and say why to look before changing anything, so the settings table confirms their list. Predictions then precede whether the Windows excerpt makes sense, which Linux labels hold which values and why “what is this machine’s IP address?” can be the wrong question; checks follow a gateway on the wrong network and the up-and-running flags. The habit to build: read, judge against the earlier lessons, and report; change nothing without authority.

2. 1. It will not connect Think 5 min

   Purpose: Build the list of settings to check from the module so far.

   Ask

   • Which settings would you look at?
   • Ask why to look before changing anything.

   Responses to expect

   • Address and gateway come first; DNS is often forgotten.
   • On screen in turns: the opening question, its answer; then the question on looking before changing, and its answer.

   Discussion pause: Write the learners’ list on the board to compare with the table.

   In the lesson window

   • Think it through: A friend’s laptop can reach nothing on the internet. Before changing anything, which settings would you want to look at, and what would each one tell you?
   • Think it through: Why look before changing anything?

3. 2. What you are looking for Explain 4 min

   Purpose: Confirm the five settings and the lesson each comes from.

   Ask

   • Which setting answers “where does traffic for other networks go?”

   Responses to expect

   • The default gateway.
   • On screen in turns: the opening; then the settings that matter, with their questions held back; the question each setting answers.

   Discussion pause: The table’s second column is held back: ask what question each setting answers, and compare with the opening list, before revealing it.

4. 3. Windows: ipconfig /all Predict 9 min

   Purpose: Read ipconfig /all and judge whether the configuration makes sense.

   Ask

   • Is anything wrong with this configuration?
   • What is wrong with the 10.4 laptop?

   Responses to expect

   • Some compare only the first two numbers.
   • On screen in turns: the opening; then the illustrative ipconfig excerpt; hyphens or colons: the same MAC address; the question on whether the configuration makes sense, and its answer; checking the configuration, starting with the network; the gateway; where the settings came from; name resolution; the check question on a gateway elsewhere, and its answer.

   Misconceptions to challenge

   • A learner may believe: “The MAC address shown is fixed in the hardware.” Respond: It is the current setting; it can be changed or randomised.

   In the lesson window

   • Think it through: Look at the excerpt. Using what you know about subnets, gateways and DHCP, is anything wrong with this configuration?
   • Check your understanding: Another laptop shows 10.4.7.20 with mask 255.255.255.0 and default gateway 10.4.8.1. What is wrong?

5. 4. Ubuntu: ip addr show Predict 5 min

   Purpose: Find the same settings in ip addr show and ip -4 route.

   Ask

   • Which labels hold the hardware and IPv4 addresses?

   Responses to expect

   • link/ether and inet usually come with one hint.
   • On screen in turns: the opening question, its answer; then the same settings on Linux; the modern Linux commands, starting with ip addr show; what each label shows; the routing table, and how to read it.

   In the lesson window

   • Think it through: Linux shows the same settings as Windows but labels them differently. In the output below, which label would you expect to show the hardware address, and which the IPv4 address?

6. 5. VyOS: show ip route Explain 3 min

   Purpose: Recall the VyOS table and what its inactive default route means.

   Ask

   • What could the router reach in that state?

   Responses to expect

   • Only its two connected networks.
   • On screen in turns: the opening; then the example routing table; what an inactive default route means.

   Misconceptions to challenge

   • A learner may believe: “A route in the table means traffic is flowing.” Respond: A route shows where traffic would go; an inactive one is not in use.

7. 6. Linux: ifconfig Predict 10 min

   Purpose: Use ifconfig to find which interface is on the lab network.

   Ask

   • What is the problem with “what is this machine’s IP address?”
   • Do up and running prove a connection?

   Responses to expect

   • Learners often pick the first interface listed.
   • On screen in turns: the opening; then the question on a machine with two adapters, and its answer; which interface matters; the practice lab and its two kinds of adapter; which interface is on the lab network, starting with counting them; the network each interface is on; the target’s network; the comparison; the flags; the result, and what it does not show; reading ifconfig output; ifconfig and ip addr; the check question on up and running, and its answer.

   Misconceptions to challenge

   • A learner may believe: “An interface has exactly one IP address.” Respond: It can have several, including IPv4 and IPv6 together.

   If the explanation does not land: Have learners write each interface’s network address beside it before comparing with the target.

   In the lesson window

   • Think it through: A machine has two network adapters, each with its own address. Someone asks “what is this machine’s IP address?” What is the problem with the question?
   • Check your understanding: Both interfaces in the example are flagged as up and running. Does that prove the testing machine can reach the target?

8. 7. Other useful commands Explain 2 min

   Purpose: Complete the toolkit and the rule about viewing, not changing.

   Ask

   • Which command shows the ARP cache on Windows?

   Responses to expect

   • arp -a.
   • On screen in turns: the opening; then look before you change.

9. 8. 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

   • Names-not-numbers tests DNS; the /20 tests subnetting; view-only tests authorisation.
   • On screen in turns: the opening; then the question on names but not numbers, and its answer; the question on which network it is, and its answer; the question on view-only permission, and its answer.

   To go further

   • Which command would you use on Linux to confirm the default gateway, and what would you expect it to print?

   In the lesson window

   • Apply it: A laptop can open websites by IP address but not by name. Which field in ipconfig /all would you check first?
   • Apply it: A Linux server shows inet 172.16.9.40/20. Which network is it on?
   • Apply it: On a lab machine you notice the default route looks wrong, but you are allowed only to view settings. What do you do?

10. 9. 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 ifconfig questions link to the Linux step.
    • On screen in turns: the opening; then the revision questions one at a time, each followed by its answer; where to practise next.

11. 10. What to remember Consolidate 3 min

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

    Ask

    • Without looking: two signs that a configuration is wrong.

    Responses to expect

    • A gateway outside the network; a 169.254 address.
    • On screen in turns: the opening; then the summary; the key terms; the common misunderstandings.

12. 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

    • Five settings explain most problems.
    • Different commands, the same settings.
    • Judge them against subnets, gateways and DHCP.
    • Several interfaces: find the one on your network.
    • Settings show intent, not proof; read, report, and change nothing without authority.

Consolidation

• Five settings explain most problems.
• Different commands, the same settings.
• Judge them against subnets, gateways and DHCP.
• Several interfaces: find the one on your network.
• Settings show intent, not proof; read, report, and change nothing without authority.