# Response Codes

These are the most common response codes you can get while using Oxylabs Dedicated ISP Proxies.

<table><thead><tr><th width="166">Response code</th><th width="254.33333333333331">Error message</th><th>Description</th></tr></thead><tbody><tr><td><code>407</code></td><td><code>Proxy Authentication Required</code></td><td>User credentials are not provided / are incorrect / the user is connecting from an IP that is not whitelisted.</td></tr><tr><td><code>504</code></td><td><code>Gateway Timeout</code></td><td>A proxy server timed out, waiting for a response from the target server. It usually takes about 60s.</td></tr><tr><td><code>503</code></td><td><code>Service Unavailable</code></td><td>Failed to connect to the target server. DNS failure to resolve the target server address.</td></tr><tr><td><code>404</code></td><td><code>Not Found</code></td><td>The domain specified could not be found.</td></tr><tr><td><code>500</code></td><td><code>Internal Server Error</code></td><td>We had a problem with our server. Try again later.</td></tr><tr><td><code>429</code></td><td><code>Too Many Requests</code></td><td>User has reached the thread/concurrent session limit.</td></tr></tbody></table>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://developers.oxylabs.io/products/proxies/dedicated-isp-proxies/self-service/response-codes.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.