Break the boot at three different stages and identify each from the screen

short · 50 min · Objective 3.1

Task

Deliberately produce a firmware-stage, a bootloader-stage and a driver-stage failure on the guest, and record what each one looks like before repairing it. Identifying the stage from what appears on the screen is the whole diagnosis, and the repair follows from it.

Steps

  1. Snapshot, then change the firmware boot order or mode so the guest cannot find its disk. Record what appears in lab/boot3/stages.csv with header stage,what_you_changed,what_appears,tool_that_fixes_it. Repair it and confirm it boots.
  2. Snapshot, then damage the boot configuration. Record the row, repair it from the recovery environment using the boot repair commands, and save the output to lab/boot3/bootrec.txt.
  3. Snapshot, then disable or corrupt a driver needed at boot. Record the row, then repair it from safe mode or from a restore point.
  4. For each stage, record the question that distinguished it in lab/boot3/questions.md -- including the one that separates a kernel failure from a desktop failure.
  5. Write lab/boot3/rescue.md listing what you would copy off a machine before a rebuild, and how you would do it from the recovery command prompt.

Verify

awk -F, 'NR>1 && NF>=4 {n++} END {print n" stage(s) produced"}' lab/boot3/stages.csv
awk -F, 'NR>1 {print $4}' lab/boot3/stages.csv | sort -u | wc -l
grep -Eic 'bootrec|bcdboot|bcdedit' lab/boot3/bootrec.txt
grep -Ec '^[-*0-9]' lab/boot3/questions.md
grep -Eic 'sign-in screen|logon screen' lab/boot3/questions.md
grep -Ec '^[-*0-9]' lab/boot3/rescue.md

Three stages with three distinct repair tools, boot repair output captured, and the questions note naming the sign-in screen test. Three stages all repaired the same way means two of them were the same stage.

Notes

The sign-in screen is the discriminator worth memorising: if you can reach it, the kernel and drivers are fine and the problem is above them, which removes half the search space in one observation.

This is an independent study companion for CompTIA A+ Core 2 220-1202 and is not produced by or endorsed by CompTIA.