Field notes

Start with the smallest useful test.

A short checklist for separating endpoint failures from route and transport problems.

1. 01

   Resolve

   Confirm the expected address from more than one resolver. A correct cached answer does not prove the current record is correct.

2. 02

   Connect

   Test the actual transport and port. Keep DNS, TCP and application responses as separate observations.

3. 03

   Compare

   Repeat the same check from a second network. Differences between paths are often more useful than a single successful result.

4. 04

   Record

   Keep timestamps, resolved addresses and response times. A short timeline makes intermittent failures much easier to interpret.