Unavailable is a useful result
A timeout means the check did not finish. A block means the destination refused automated access. A 404 or 410 indicates a missing resource. An empty or error-filled 200 response remains unverified.
Identity changes are different
If the destination responds but names a different model, it is quarantined as a mismatch. We preserve the disagreement rather than rewriting the source title or guessing a replacement URL.
What to do next
Open the original source record, compare its current fields and wait for a later exact destination check. Never modify product identifiers or substitute an agent homepage as if it were the product.