You fixed it, but can you prove it?
A desk cannot reach the server. You change one setting and it works. You tell the manager, "Fixed."
She asks, "What was wrong? Why that change? Is everything else still fine?" If you cannot answer, the fix is only a hope. Evidence turns it into a fact.
By the end of this lesson
Note
I can make one fix, give the reason for it and prove it with a second round of tests.
Key words
| Word | What it means |
|---|---|
| Remedial action | a change you make to repair a fault |
| Justify | to give the reason a choice was right |
| Retest | to run the same tests again after a change |
| Regression | something that worked before and is broken by a change |
| Change log | a record of each change, who made it and why |
| Return route | the route that lets a reply travel back to the sender |
| Network | computers and devices joined together so they can share data |
| Router | a device that passes messages from one network to another |
| Procedure | a set of steps that is always followed in the same way |
| Ping | a tool that sends a small message to an address and waits for a reply |
The cells students fill in are left blank in this preview.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
This is practice
Important
The real Task 2 gives you its own network file and its own way of recording fixes. Here you use real commands in a lab. Ask your teacher what the real task expects you to record.
Set up: router A knows the way out
sudo ip netns exec r1 ip route replace 10.0.3.0/24 via 10.0.12.2A command for the lesson’s lab terminal. It is shown here and not run.
Test 1: ping the far host
sudo ip netns exec h1 ping -c 2 -W 1 10.0.3.2A command for the lesson’s lab terminal. It is shown here and not run.
Test 2: trace the path
sudo ip netns exec h1 traceroute -n -w 1 -m 3 10.0.3.2A command for the lesson’s lab terminal. It is shown here and not run.
Test 3: does the request reach router B?
sudo ip netns exec r2 timeout 4 tcpdump -ni to-r1 -c 1 icmp & sleep 1; sudo ip netns exec h1 ping -c 1 -W 1 10.0.3.2; waitA command for the lesson’s lab terminal. It is shown here and not run.