> The domain in the first field of the line has no working DNS record: the ad system may have been retired or merged, or the domain is misspelled. The line can't be validated.

Source: https://appsupplyindex.com/fix/ad-system-domain-does-not-resolve · Updated: 2026-10-07 · License: CC BY 4.0 (App Supply Index)

---
[Learn](https://appsupplyindex.com/learn/) · How to fix

# What does it mean when an ad system domain in app-ads.txt doesn't resolve?

Updated Oct 7, 2026 · data from 12 App Store genres · top free + top grossing charts · US · iOS + Android

**Short answer:** The domain in the first field of the line has no working DNS record: the ad system may have been retired or merged, or the domain is misspelled. The line can't be validated.

**434 of 883**
ad-monetized top US apps in this index have this finding (49%)

## Why it matters

Lines for domains that don't exist add nothing for buyers.

If such a domain is registered again by someone else, its new holder would appear authorized by your file, which is a reason to remove these lines rather than leave them.

## How to fix it

1. Check the domain for typos (for example, a missing or doubled part).
2. If the company merged into another ad system, replace the line with the one the new owner provides.
3. Otherwise remove the line.

Before

```
appnexus.comappnexus.com, 1234, RESELLER
```

After

```
appnexus.com, 1234, RESELLER
```

## Apps with this finding

Each report lists the exact lines involved.

- [Word Search Explorer®](https://appsupplyindex.com/app/ios-1602508478) · PlaySimple Games Pte Ltd
- [Sled Surfers](https://appsupplyindex.com/app/ios-6744975195) · CRAZY LABS BY TABTALE , G.P.
- [Glow Fashion Idol](https://appsupplyindex.com/app/ios-6446197181) · CRAZY LABS BY TABTALE , G.P.
- [Lamar - Idle Vlogger](https://appsupplyindex.com/app/ios-1595314851) · CRAZY LABS BY TABTALE , G.P.
- [My Sticker Room - Decor Game](https://appsupplyindex.com/app/ios-6743738094) · SayGames LTD
- [Meowdoku!](https://appsupplyindex.com/app/ios-6761760135) · OAKEVER GAMES PTE. LTD.
- [Vita Mahjong](https://appsupplyindex.com/app/ios-6468921495) · VITA STUDIO PTE. LTD.
- [Amaze GO!](https://appsupplyindex.com/app/ios-6758326278) · OAKEVER GAMES PTE. LTD.
- [Colorever: Gem Art Puzzle](https://appsupplyindex.com/app/ios-6761757565) · OAKEVER GAMES PTE. LTD.
- [Mystery Town: Merge Games](https://appsupplyindex.com/app/ios-6503603603) · Cedar Co., Limited
- [Jigsawcard Solitaire Puzzle](https://appsupplyindex.com/app/ios-6754900673) · OAKEVER GAMES PTE. LTD.
- [Block Blast！](https://appsupplyindex.com/app/ios-1617391485) · ARETIS LIMITED

[All apps →](https://appsupplyindex.com/apps)

## Questions

### How do you decide a domain doesn't resolve?

Neither the domain nor its www host returns an address in DNS at crawl time.

## Related

- [What is app-ads.txt?](https://appsupplyindex.com/learn/what-is-app-ads-txt)
- [DIRECT vs RESELLER](https://appsupplyindex.com/learn/direct-vs-reseller)
- [How the index checks files](https://appsupplyindex.com/methodology)

Based on the [IAB Tech Lab
ads.txt/app-ads.txt](https://iabtechlab.com/ads-txt/) and [sellers.json](https://iabtechlab.com/sellers-json/)
specifications. Numbers are automated observations of public files on the date above.