Lion Cipher Lab
Watch DHCP Hand Out Your IP Address (the DORA Exchange)
- Foundations
- Beginner
- ~35 min
- Free · no account required
Why it matters
Every device on a network faces the same chicken-and-egg problem: to talk to anything it needs an IP address, but to ask for an IP address it has to talk to something. DHCP solves it, and it runs BEFORE DNS and before any TCP connection — it is quite literally the first conversation your laptop has when it joins a network. Watching the four DORA packets turns 'my Wi-Fi just works' into something you understand and can troubleshoot: the dreaded 169.254 address, a phone that won't get online, a rogue DHCP server quietly handing out a poisoned gateway. It is a staple networking-interview…
What you'll learn
- packet capture
- the DHCP DORA exchange
- Wireshark display filters (bootp/dhcp)
- reading DHCP options (message type, gateway, DNS, lease)
- recognizing APIPA / no-DHCP failures
- spotting rogue DHCP risk
Steps in this lab
- The chicken-and-egg problem DHCP solves, in one breath
- Install Wireshark (from wireshark.org and nowhere else)
- Find and start capturing on your active adapter — BEFORE you renew
- Force a fresh lease — WINDOWS path
- Force a fresh lease — LINUX path
- Stop the capture and filter to just DHCP
- Walk the four messages — D, O, R, A
- Read the fields that actually hand you an address
- Why this matters for security — and the failure you'll actually meet
- If you captured nothing — the quick fixes