Stranded on 169.254 — Diagnosing an APIPA Fallback

N10-009: 1.7 · 1.4 · 5.5  |  AP Networking: 2.1 · 2.2 · 3.6
You volunteer as the net-tech at Tinkergrove Makerspace. This morning every bench machine came up but nobody can reach the print queue or the internet — yet the machines can still "see" each other. The makerspace runs a flat 10.42.7.0/24 network: gateway 10.42.7.1, and a small server core-srv (10.42.7.10) that hands out leases. Your job: figure out why the benches are islanded, fix the source, and prove the network is back.

Bench consoles

frontdesk-pc>

Task checklist

  1. ✓Run ipconfig on all three benches and read their addresses.Switch between frontdesk-pc, laser-cut-pc, and vinyl-pc.
  2. ✓From a bench, show it can ping a peer bench but not the gateway.Try ping 10.42.7.1 and ping a peer's address.
  3. ✓Open core-srv and confirm the Bench-Net scope is the cause.
  4. ✓Activate the scope so the server starts answering.
  5. ✓On a bench, pull a real lease with ipconfig /renew.
  6. ✓Prove the fix: ping the gateway from a leased bench and succeed.

Check your understanding

Q1What single command, run on a bench, pulls a fresh address from the server once the scope is fixed?
Q2Which address range is the tell-tale sign of APIPA self-assignment?
Q3While islanded, the benches could ping each other but not the gateway. Why?
Q4What subnet mask does a Windows host apply to an APIPA address?
Q5What was the underlying cause of every bench falling back to APIPA?
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