How do you distinguish an intentional open from broken connectivity?

Short Answer

Not every unconnected pin is a bug — some are deliberately left open by design intent, a tie-off policy, or a black-box boundary that simply doesn't drive that signal in this configuration. " An intentional open should have a paper trail: interface documentation, a tie-off strategy, or a synthesis log entry explaining why that pin is unconnected.

Technical Explanation

• g. optimized-away logic, unused output of a configuration mux).
• "
• Contrast this with broken connectivity: an open with no recorded reason, no tie-off policy covering it, and no synthesis explanation is a real defect until proven otherwise — treat silence as evidence of a bug, not evidence of intent.
• Bottom line: intention requires recorded ownership. If you can't point to who decided this pin should be open and why, don't waive it — chase it down as a potential defect.

What To Check

• Warning sign: An unused output is harmless, but a floating enable has the same superficial 'open' label.
• Inspect: Compare one named object across the related reports; the same object should tell a consistent story.
• Correct: Fix functional opens upstream; waive only named, reviewed objects with a reason and rerun criterion.

Healthy, Suspicious & Hard-stop Results

• Expected: Trace the object to interface intent, tie-off policy, black-box boundary, and synthesis log; intention requires recorded ownership.
• Stop before floorplanning when required logic or timing coverage is missing or unexplained.

What The Interviewer Is Testing

Be ready to explain why this matters before floorplanning.

Follow-up Question & Model Response

Model response: “I would save the report, inspect one affected object in the correct block and scenario, and make or request this correction. ”