Diagnose a configuration from four commands and write down what each proved

short · 30 min · Objective 1.2

Task

Run the five diagnostic network commands on a machine, record what each one returned, and state what each result eliminated. The exercise is the reasoning rather than the typing: the value of ipconfig /all is that four of its values each rule out a different fault.

Steps

  1. Run the address command for your platform and write lab/cli/config.csv with header value,what_it_is,what_it_rules_out covering address, mask, gateway, DNS servers and DHCP server.
  2. Ping the gateway, then an address on the internet, then a name. Record all three in lab/cli/chain.csv with header target,result,layer_proved.
  3. Run the name resolution command against a name and record which server answered in lab/cli/dns.txt.
  4. Run the connections command and write lab/cli/listening.csv with header port,state,process,expected listing at least five listening ports on the machine, marking whether you expected each one. expected is yes or no, lowercase. Keep commas out of every field: the Verify splits on them, and one comma shifts every column after it.
  5. Write lab/cli/elevation.md naming three commands that need administrative rights, and describing what the file system virtualisation trap does to a write that is not elevated.

Verify

These checks run in a POSIX shell: Terminal on macOS or Linux, and on Windows Git Bash (it comes with Git for Windows) or WSL. A stock Windows PowerShell or Command Prompt has no awk or grep, so there the first line fails.

awk -F, 'NR>1 && NF>=3 {n++} END {print n+0" value(s) explained"}' lab/cli/config.csv
awk -F, 'NR>1 && NF>=3 {n++} END {print n+0" test(s) in the chain"}' lab/cli/chain.csv
grep -c . lab/cli/dns.txt
awk -F, 'NR>1 && NF>=4 {n++} END {print n+0" listening port(s)"}' lab/cli/listening.csv
awk -F, 'NR>1 && $4 ~ /no/ {n++} END {print n+0" unexpected port(s)"}' lab/cli/listening.csv
grep -Eic 'administrator|elevat|virtualis|virtualiz' lab/cli/elevation.md

Five configuration values each with a fault it rules out, three chain tests, and five listening ports assessed. An unexpected port is a finding worth following up rather than a mistake in the lab.

Notes

The what_it_rules_out column is the whole exercise. An address beginning 169.254 rules out a working DHCP server and rules IN a functioning adapter and stack, and being able to say both halves is what distinguishes reading output from understanding it.

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