Cannot find usable delegation set when DNS to aws nameservers is blocked

```
Failed to find existing usable delegation set
```
Will be reported when dns lookup directly to AWS name server faills, this happens to certain VPN or private network where DNS lookup other than the default one is blocked.

<img width="1862" height="414" alt="Image" src="https://github.com/user-attachments/assets/afd8fa83-26a6-4f93-9d0e-3ebfb1e323e3" />