How I combine small network tools when debugging connectivity

Network debugging usually needs more than one clue. DNS, IPs, ports, URLs, and headers each answer a different question.

I use Network tools for the quick version of this task, then I review the output before relying on it.

The simple idea

Network debugging usually needs more than one clue. DNS, IPs, ports, URLs, and headers each answer a different question.

The tool is a shortcut for the mechanical work. It does not remove the need to understand what the result means.

Step 1: Start with the URL being tested

Start with the URL being tested.

Step 2: Parse the URL into host, path, and query

Parse the URL into host, path, and query.

Step 3: Look up DNS records for the host

Look up DNS records for the host.

Step 4: Check the resolved IP context if needed

Check the resolved IP context if needed.

Step 5: Check whether the expected port and protocol make sense

Check whether the expected port and protocol make sense.

Step 6: Inspect HTTP headers after the server responds

Inspect HTTP headers after the server responds.

Step 7: Write down each finding instead of jumping to conclusions

Write down each finding instead of jumping to conclusions.

My checklist

Before I trust the result, I check:

• Start with the URL being tested.
• Parse the URL into host, path, and query.
• Look up DNS records for the host.
• Check the resolved IP context if needed.
• Check whether the expected port and protocol make sense.
• Inspect HTTP headers after the server responds.
• Write down each finding instead of jumping to conclusions.

That review step is what keeps a quick tool from becoming a quick mistake.