Investigate how app.example.test is delegated from the root and identify where resolution fails.
Use dig.
Which command is appropriate?
dig +trace follows referrals from the root through authoritative servers, unlike a normal recursive resolver query.
Detailed explanation
dig app.example.test +shortIncorrect. +short prints the answer but does not show delegation.
dig app.example.test +tcpIncorrect. +tcp only selects transport and does not trace referrals.
dig app.example.test +noall +answerIncorrect. It shows the answer section only.
dig app.example.test +traceCorrect. +trace displays the iterative delegation path.
Try it yourself
An example you can run in a temporary verification environment.
dig -h 2>&1 | sed -n '1,8p'Expected result
digの使用方法Key points
- +trace follows delegation
- Starts at the root
- Different from recursive lookup
Notes
- Environment: BIND dig help / 外部問い合わせなし
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Interface counters
Kernel-maintained counts of packets, errors, and drops at an interface.
Socket
A local or remote endpoint associated with a transport protocol and process.
Path tracing
A diagnostic method that observes hops and path limits toward a destination.