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Aim / Objective

To understand IPv4 structure, classes (A, B, C, D, E), CIDR notation, and RFC 1918 Private IP ranges versus Public IPs; calculate subnet masks, network addresses, broadcast addresses, and usable host ranges; and manually configure static IPv4 parameters on Windows and Linux systems.

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Hardware & Software Requirements

Hardware Components

✓ Two or more desktop computers connected to a common local Ethernet switch
✓ Cat6 Ethernet patch cables
✓ Broadband Router with active Internet connection (for comparing Public WAN IP vs Private LAN IP)

Software, OS & Tools

✓ Windows 10/11 (`ncpa.cpl`, `ipconfig`, `route`, `ping`)
✓ Linux Terminal (`ip addr`, `ip route`, `nmcli`, `netplan`)
✓ Web Browser visiting public IP verification services (e.g. `icanhazip.com` or `ifconfig.me`)

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Teacher's Lab Delivery Guide

Essential briefing notes, pedagogy, and setup tips for lab instructors

Faculty Exclusive

⏱ 5-Minute Pre-Lab Lecture Briefing:

Teach IPv4 as a 32-bit binary number divided into 4 octets separated by dots. Highlight that an IP address without a Subnet Mask is meaningless. Write the 3 RFC 1918 Private ranges on the board and explain NAT: why your home/lab has 192.168.x.x internally, but the entire world sees only one public IP on your router.

📝 Key Concepts to Write on Whiteboard:

IPv4 anatomy: 32 bits, 4 Octets (8 bits each), Network ID vs Host ID
Classful addressing: Class A (1-126, /8), Class B (128-191, /16), Class C (192-223, /24), Class D (Multicast), Class E (Experimental)
RFC 1918 Private IP Ranges (Non-routable over the public Internet):
- 10.0.0.0 to 10.255.255.255 (10.0.0.0/8)
- 172.16.0.0 to 172.31.255.255 (172.16.0.0/12)
- 192.168.0.0 to 192.168.255.255 (192.168.0.0/16)
Subnet Mask & CIDR (Classless Inter-Domain Routing): /24 = 255.255.255.0, /25 = 255.255.255.128, etc.
Calculating Network ID (all host bits 0) and Broadcast ID (all host bits 1)
Static IP configuration vs Dynamic DHCP assignment

⚙ Pre-Class Lab Setup:

Assign distinct static IP subnets to adjacent student pairs (e.g., PC-A: 192.168.10.10/24, PC-B: 192.168.10.20/24) so they can test peer-to-peer pinging and see what happens when subnet masks don't match.

⚠ Common Student Pitfalls & Fixes:

Students assign the Network Address (ending in `.0`) or the Broadcast Address (ending in `.255` in a /24) to a host PC, which is illegal. Emphasize usable host range: $2^H - 2$.

🛡 Lab Safety & ESD Precautions:

Document original DHCP network adapter settings before entering static IP addresses so students can restore normal lab internet connectivity at the end.

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Step-by-Step Practical Procedure

1

Examine Current IP Configuration via Terminal

Open Command Prompt (Windows) or Terminal (Linux). View current IP address, subnet mask, default gateway, and DNS servers assigned by DHCP.

Command / Action:

Windows: ipconfig /all || Linux: ip -c a

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Teacher Note / Pro-Tip: Notice whether your IP begins with 10.x, 172.16-31.x, or 192.168.x (Private IP).

2

Compare Private LAN IP with Public WAN IP (NAT Concept)

Compare your local private IP with the public IP assigned by your ISP by querying an external web service via curl. Notice that multiple lab PCs share the identical public IP through NAT (Network Address Translation).

Command / Action:

curl https://ifconfig.me/ip

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Teacher Note / Pro-Tip: Private IPs are dropped by internet routers; NAT converts private IP:port pairs into public IP:port sessions.

3

Subnetting Calculation Exercise

Given subnet `192.168.50.0/26`: Calculate the Subnet Mask, number of subnets, total addresses ($2^6 = 64$), usable host addresses ($64 - 2 = 62$), Network Address (`192.168.50.0`), First Host (`192.168.50.1`), Last Host (`192.168.50.62`), and Broadcast Address (`192.168.50.63`).

Command / Action:

Formula: Usable Hosts = 2^(32 - CIDR) - 2

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Teacher Note / Pro-Tip: Subtracting 2 accounts for the unusable Network ID (all host bits 0) and Broadcast ID (all host bits 1).

4

Configure Static IPv4 Address on Windows

Press `Win + R`, type `ncpa.cpl` to open Network Connections. Right-click Ethernet -> "Properties" -> Double-click "Internet Protocol Version 4 (TCP/IPv4)". Select "Use the following IP address". Enter IP: `192.168.50.10`, Subnet Mask: `255.255.255.192` (/26), Default Gateway: `192.168.50.1`. Add Preferred DNS: `8.8.8.8`. Click OK.

Command / Action:

Shortcut: Win + R -> ncpa.cpl -> IPv4 Properties

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Teacher Note / Pro-Tip: Make sure adjacent student PC is configured on the same subnet (e.g. `192.168.50.11`).

5

Configure Static IPv4 Address on Linux (CLI)

In Linux, configure a static IP on network interface `eth0` or `enp0s3` using the `ip` command or `nmcli`.

Command / Action:

sudo ip addr add 192.168.50.12/26 dev eth0 && ip route show

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Teacher Note / Pro-Tip: To make persistent on Ubuntu, edit `/etc/netplan/01-netcfg.yaml`.

6

Verify Peer Connectivity & Cross-Subnet Isolation

Ping the adjacent machine on the same subnet (`ping 192.168.50.11`). Next, temporarily change the IP of one machine to a different subnet (`192.168.60.10/24`) without a router and observe that ping fails, proving subnet broadcast isolation.

Command / Action:

ping 192.168.50.11 -t

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Teacher Note / Pro-Tip: Hosts on different subnets require a Layer 3 router to forward packets between them.

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Interactive Hands-On Lab Simulator

Practice and test concepts virtually before or after performing on physical lab equipment

Live Interactive

Loading simulator...

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Observations & Student Lab Record

Students are required to record the following measured parameters, hardware specifications, and output status into their physical lab journals:

Parameter	Class A Example	Class B Example	Class C Example	Subnetted (/26) Example
IP / CIDR Notation	10.50.1.10 /8	172.16.20.5 /16	192.168.1.100 /24	192.168.50.10 /26
Subnet Mask	255.0.0.0	255.255.0.0	255.255.255.0	255.255.255.192
Network ID	10.0.0.0	172.16.0.0	192.168.1.0	192.168.50.0
Broadcast Address	10.255.255.255	172.16.255.255	192.168.1.255	192.168.50.63
Usable Host Range	10.0.0.1 - 10.255.255.254	172.16.0.1 - 172.16.255.254	192.168.1.1 - 192.168.1.254	192.168.50.1 - 192.168.50.62
Total Usable Hosts	16,777,214 hosts	65,534 hosts	254 hosts	62 hosts

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Conclusions & Learning Outcome

IPv4 addressing, classification, and subnetting were explored theoretically and verified practically. Static IP parameters were configured in both Windows (`ncpa.cpl`) and Linux (`ip addr`). The separation between private local subnets and public routable IPs via Network Address Translation (NAT) was confirmed.

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Oral Exam & Viva Questions with Answers

Essential questions asked by external examiners and lab evaluators (Accordion UI)

Answer:

1. Class A Private: `10.0.0.0` to `10.255.255.255` (`10.0.0.0/8`)\n2. Class B Private: `172.16.0.0` to `172.31.255.255` (`172.16.0.0/12`)\n3. Class C Private: `192.168.0.0` to `192.168.255.255` (`192.168.0.0/16`)