A Professor Wingman Class 404
NetMgmt.Lab

Week 5

IP Addressing, Subnet Masks, and Connectivity Testing

Focus on Layer 3: IP addresses, subnet masks, and default gateways — and the tools that verify they work.

Lesson recap

Every device on a network needs three things to talk to the outside world: an IP address (its identity), a subnet mask (the size of its neighborhood), and a default gateway (the door out of the neighborhood). When a connection fails, the question is always 'which of those three is wrong?' Ping tells you whether a host responds. Traceroute tells you the path packets take and where they die. By the end of this week you should be able to look at any `ipconfig` output and predict whether a machine can reach Google before you even try.

Learning goals

  • Explain IP addresses, subnet masks, and default gateways
  • Identify basic IPv4 information on a computer
  • Use ping to test loopback, gateway, and external addresses
  • Use traceroute to view the path packets take
  • Document connectivity test results

Key terms

IP Address

A numeric identifier for a device on a network (e.g. 192.168.1.42).

Subnet Mask

Defines which part of the IP is the network and which is the host (e.g. 255.255.255.0).

CIDR Notation

Shorthand for subnet mask, e.g. /24 means 255.255.255.0.

Default Gateway

The router IP a device uses to reach other networks.

DHCP

Dynamic Host Configuration Protocol — automatically assigns IP info.

Static IP Address

A manually configured IP address.

Private IP Ranges

10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 — not routable on the internet.

APIPA (169.254.x.x)

A self-assigned IP — almost always means DHCP failed.

Ping

ICMP echo tool that tests reachability.

Traceroute / tracert

Shows each router (hop) between you and a destination.

Curated videos

IP Address — IPv4 vs IPv6 Tutorial

PowerCert Animated Videos

What is Subnetting? — Subnetting Mastery Part 1

Practical Networking

Seven Second Subnetting

Professor Messer

Commands

ipconfig
ipconfig /all
ipconfig /release ipconfig /renew
ip addr
ip route
ping <gateway-ip>
tracert google.com
traceroute google.com

Checkpoint checklist

Sign in to save your progress across devices.
  • Find your IP address
  • Review loopback ping
  • Ping your default gateway
  • Trace a network path
  • Complete IP address practice
  • Create connectivity report
  • Saved required evidence
  • Answered the reflection questions

Pro tips from the instructor

  • ★If your IP starts with 169.254, your PC never got a DHCP lease — check the cable and the DHCP server before anything else.
  • ★You can ping the gateway but not the internet? The router has no working WAN connection. Stop blaming the PC.
  • ★tracert that ends in `* * *` doesn't always mean the path is broken — many routers silently drop ICMP. Use it as a hint, not a verdict.

Try this — stretch exercises

Optional hands-on practice that goes beyond the workbook. Check items off as you complete them — progress saves in this browser.

0/2
  • Calculate by hand: how many usable hosts does a /27 subnet have? (Hint: 2^5 − 2)
  • Compare `tracert google.com` from your home and from your phone tethered. Different first hop = different ISP path.

Files to save this week

  • 📁 Week05_IPConfig_YourLastName.png
  • 📁 Week05_PingLoopback_YourLastName.png
  • 📁 Week05_PingGateway_YourLastName.png
  • 📁 Week05_Tracert_YourLastName.png
  • 📁 Week05_ConnectivityReport_YourLastName