Dns Web Hosting Cname

How to Properly Redirect a Subdomain Using CNAME Records

Redirecting a subdomain from one host to another can be tricky, especially if you’re new to DNS management. If you’ve encountered a ‘400 Bad Request’ error while attempting to set this up, you’re not alone. In this blog post, we’ll guide you through the process of correctly configuring CNAME records to achieve a seamless redirect.

Understanding the Problem

You have two hosts, and you want to point a subdomain on Host One to a subdomain on Host Two. Your initial setup might look something like this:

subdomain.hostone.com --> subdomain.hosttwo.com

In your attempt to make this redirect, you added a CNAME record in Host One pointing to subdomain.hosttwo.com, but instead of a proper redirect, you encountered a ‘400 Bad Request’ error.

The Solution

To resolve this issue, let’s break down the steps to ensure everything is set up correctly.

1. Correct Your CNAME Record Setup

When adding a CNAME record, it’s crucial to configure it properly. Here’s how you should set your CNAME record:

  • CNAME Record Format:
    • Instead of specifying the full URL, use just the subdomain.
    • Change the entry from: 
      subdomain.hostone.com CNAME subdomain.hosttwo.com
    • To: 
      subdomain CNAME subdomain.hosttwo.com

This adjustment ensures that your DNS knows that the subdomain is an alias to subdomain.hosttwo.com, without needing the full domain in the CNAME alias.

2. Verify Domain Access and Logs

After making changes to your CNAME record, it’s crucial to check if everything is working smoothly. Here’s what to do:

  • Log into Host Two: Access subdomain.hosttwo.com directly to confirm that it is online and functioning as expected.
  • Check Logs: Look at the server logs for subdomain.hosttwo.com to see if there are any requests coming through from subdomain.hostone.com. This can help diagnose if the request is hitting the correct endpoint or encountering any server-side issues.

3. Potential Issues to Look For

If you’re still encountering the ‘400 Bad Request’ error after adjusting the CNAME record, consider the following:

  • Propagation Time: Changes to DNS records may take some time to propagate. Allow at least a few hours before testing again.

  • Server Configuration: Ensure that the server hosting subdomain.hosttwo.com is configured to accept traffic from subdomain.hostone.com. Sometimes, servers might reject requests that originate from an unexpected domain.

  • SSL/TLS Certificates: If your sites are secured with HTTPS, ensure that your certificates are correctly set up for both subdomain.hostone.com and subdomain.hosttwo.com.

Conclusion

Setting up a subdomain redirect using CNAME records can sometimes be challenging, but by following the steps above, you can navigate this task with confidence. Always remember to check your DNS settings carefully and monitor server logs to troubleshoot any unexpected errors. With the right approach, you can achieve a seamless redirect between your hosts, enhancing your site’s user experience.

If you found this guide helpful, feel free to share your experiences or any additional questions in the comments below!