The preferred address should open without a redirect, while every existing alternative should reach it in no more than one step. Whether the final address is internal or external does not change the redirect count.
Simple browser check
- Open Developer Tools and select the Network tab.
- Enable Preserve log.
- Enter the address being tested and open the page.
- Review the document sequence and 301, 302, 307 or 308 responses.
- Repeat for HTTP/HTTPS and WWW/non-WWW variants.
Terminal check
Inspect the first response without following it:
curl -sS -I --max-redirs 0 http://www.example.com/
Inspect the complete chain:
curl -sS -I -L --max-redirs 10 \
-o /dev/null \
-w 'redirects=%{num_redirects}\nfinal=%{url_effective}\nstatus=%{http_code}\n' \
http://www.example.com/
redirects=0 is normal for the preferred address. redirects=1 is normal for an alternative. A value of 2 or more is a chain that should be shortened.
If an optional WWW variant does not exist and does not redirect, that is not a double redirect. Its availability is evaluated by a separate audit item.
