Which URL is considered valid while checking for broken links

Question

I have a bunch of URLs and I'm trying to check if these URLs are valid (check for errors like 404 etc.). In such a scenario, which URLs are considered valid?

Example scenarios:

• The server responds with HTTP 3XX (Moved permanently/temporarily)

Are these URLs considered valid ?

Answer 1

I found this information in Wikipedia.

1. 1xx HTTP CODES are informational responses
2. 2xx HTTP CODES are success
3. 3xx HTTP CODES are redirection
4. 4xx HTTP CODES are client errors
5. 5xx HTTP CODES are server errors.

and some unofficial codes specific for client agent or webserver.

So not all 3XX codes are errors.