How do I troubleshoot an HTTP 400 error related to an invalid hostname in IIS?

Troubleshooting involves several steps. First, verify the URL for typos. Second, confirm the hostname resolves to the correct IP address using `nslookup` or `dig`. Third, check the IIS bindings to ensure the hostname is correctly configured and associated with the correct IP address and port. Fourth, inspect the IIS application configuration for any potential conflicts or misconfigurations.