---
title: "What affects the quality of a lookup result"
url: "https://lookvalid.com/help/about/what-affects-result-quality.md"
canonical_url: "https://lookvalid.com/help/about/what-affects-result-quality"
last_updated: "2026-10-20"
type: "conceptual"
summary: "What a lookup can and cannot tell you, where each answer comes from and how to read found false."
related: ["https://lookvalid.com/help/about/available-lookups-and-coverage.md", "https://lookvalid.com/help/billing/plans-and-credits.md"]
---

# What affects the quality of a lookup result

What a lookup can and cannot tell you, where each answer comes from and how to read found false.

## Every answer names its sources

Each response includes a `sources` list that names the datasets or checks behind the result. If a field is missing from the response, that source does not publish it, and we leave the field out instead of guessing.

## What the checks mean

- A phone numbering-plan check tells you whether a number is shaped like a real number in that country, not whether someone answers it.
- An email domain check tells you about the domain behind an address, not whether one mailbox exists.
- An IP lookup places an address in a network and a region; regions are approximate by nature.
- A domain age lookup reports the registration record, which a registry can change.

## Reading found false

`found: false` means the lookup ran and the source had no answer. It is not an error and, on a success-billed product, it costs nothing. Repeating the same lookup inside 7 days returns the stored answer, free.

## Data changes

Numbering plans, registrations and networks change daily. Cached results can be up to the cache window old, and each response shows when it was stored.

## Related

- [Which lookups are available and where they work](https://lookvalid.com/help/about/available-lookups-and-coverage.md)
- [Plans, credits and how they are spent](https://lookvalid.com/help/billing/plans-and-credits.md)