# Exercise 1 — Tracing DORA and ARP Resolution

## Scenario

A new employee's laptop won't connect properly on their first day at the office. Before escalating to IT, you want to reason through exactly what should happen when a laptop joins a network, so you know which step is actually failing.

## Deliverables

1. **DORA trace with concrete values.** A laptop with MAC address `aa:11:bb:22:cc:33` joins a network with a DHCP server at `192.168.1.1`. Write out all four DORA steps with plausible concrete values (the offered IP, subnet mask, lease time, etc.), explicitly noting which messages are broadcast and which are addressed directly.

2. **ARP trace for a same-network request.** After getting its address (`192.168.1.50`) via DHCP, the laptop needs to reach the network printer at `192.168.1.75`. Write out, step by step, the ARP exchange needed before the first packet to the printer can even be sent, including what gets cached afterward and by whom.

3. **ARP trace for a cross-network request.** The same laptop now needs to reach `8.8.8.8` (a public DNS server, on a different network entirely). Explain specifically whose MAC address gets ARP-resolved in this case, and why it is NOT `8.8.8.8`'s own MAC address — reference the theory file's explanation of ARP being confined to the local broadcast domain.

4. **Diagnosis.** The new employee's laptop successfully gets an IP address via DHCP but cannot reach anything, including devices on the same local network. Given what you now know about DORA and ARP being separate mechanisms, name one specific, plausible failure that would produce exactly this symptom (DHCP working, ARP/local connectivity not), and explain why "check the DHCP server" would NOT be where you'd look first.

## Notes

- Use realistic-looking IP and MAC addresses throughout; the specific values don't need to be "correct" for a real network, just internally consistent within your answer.