Okay, seeing a completely for a live site with blank page for demosites.demo.com (either a domain or a subdomain) can be caused by several issues, ranging from DNS configuration to server-side problems.

Here’s a breakdown of the most likely reasons and how to troubleshoot:

Apex Domain and Subdomain: DNS Propagation Issues:

• Problem: You recently set up the subdomain demosites for demo.com. DNS changes can take time (minutes to 48 hours, though usually much faster) to propagate across the internet. Your local machine or network might not have the updated DNS record yet, or it might be pointing to an old/incorrect IP address.
• Check: Use an online DNS checker tool (like dnschecker.org) and enter demosites.demo.com. See if it resolves to the correct IP address or CNAME target across different locations. Also, try clearing your local DNS cache.

Incorrect DNS Records:

• Problem: The A record (pointing to an IP address) or CNAME record (pointing to another domain name, common for platforms like Netlify, Vercel, GitHub Pages) for demosites might be incorrect in your demo.com DNS zone file.
• Check: Log into your DNS provider (where demo.com's nameservers are managed) and verify the A or CNAME record for the demosites subdomain points to the exact value required by your hosting provider.

Web Server Configuration:

• Problem: The web server (such as Apache or Nginx) hosting the site might not be configured correctly to listen for requests from demosites.demo.com. It might lack the necessary virtual host (Apache) or server block (Nginx) entry.
• Check (if managing server): Ensure the web server configuration includes an entry for demosites.demo.com and that its DocumentRoot (the directory where the website files live) is set correctly. Restart the web server after making changes.

Missing Index File:

• Problem: Web servers typically look for a default file (like index.html, index.php, index.htm) in the DocumentRoot to display when you visit the root URL. If this file is missing or named incorrectly, the server might return a blank page (or a directory listing/forbidden error, depending on the config).
• Check: Verify that an appropriate index file exists in the correct directory on the server where demosites.demo.com is supposed to point.

File Permissions:

• Problem: The web server process might not have the necessary permissions to read the website files (especially the index file) or execute script files (like PHP).
• Check (if managing server): Ensure file permissions are set correctly (e.g., often 644 for files and 755 for directories) and that the files are owned by the appropriate user/group for the web server.

Server-Side Script Errors (PHP, Node.js, etc.):

• Problem: If the site uses server-side scripting (like PHP), a critical error occurring before any output is generated can result in a blank white screen (sometimes called the "White Screen of Death" or WSOD in WordPress/PHP contexts). Error reporting might be turned off in the production environment.
• Check:
• Enable Error Display (Development Only!): Temporarily modify settings (e.g., php.ini or via .htaccess for PHP) to display errors directly in the browser. Do not leave this on for a live site.
• Check Server Error Logs: This is the best way. Look in the web server's error log (error.log for Apache/Nginx) and any specific PHP error logs (php_error.log, etc.). These logs almost always contain details about fatal errors.

Hosting Platform Issues (Netlify, Vercel, etc.):

Problem: If using a platform like Netlify, Vercel, GitHub Pages, etc.:

The deployment might have failed.

The custom domain (demosites.demo.com) might not be correctly linked to the deployed site within the platform's dashboard.

There might be an issue with the build process.

• Check: Log in to your hosting platform's dashboard. Verify the deployment status and custom domain configuration, and check the build logs.
• .htaccess File Errors (Apache):
• Problem: A syntax error or incorrect rule in the .htaccess file can cause an Internal Server Error (500), which sometimes manifests as a blank page if error reporting is suppressed.
• Check: Temporarily rename the .htaccess file to something like .htaccess.bak and see if the page loads (it might look unstyled, but if it loads something, the .htaccess file is the likely culprit). Check the server error logs for details.

Troubleshooting Steps:

• Check DNS Propagation: Use an online tool.
• Verify DNS Records: Check your DNS provider settings.
• Check Hosting Platform Dashboard: Look for deployment/domain errors.
• Check Server Error Logs: This is often the most informative step.
• Try Accessing a Specific File: Upload a simple test.html file to the site's root directory and try accessing demosites.demo.com/test.html. If this works, the issue is likely with your index file or application code. If it doesn't, the problem is likely DNS or server configuration.
• Clear Browser Cache: Rule out simple browser issues.

Start with DNS and work your way towards the server and code-level checks. Error logs are your best friend here!

Subdomain=demosites

Apex Domain      =demo.com     

Ex. Site (subdomain)- demosites.demo.com

Suggestion: Maintain a log or activity file, or a doc with screenshots of the tasks with notes (that changed) while performing actions, and also keep patience till the propagation timing threshold (avoid repetitive tasks)

Except for these, what technical strategies have helped you solve with a website/blog that live in blank page status? Please share your valuable experience with us in the comments.

Author, 

Momenul Ahmad

I'm Momenul Ahmad, Digital Marketing Strategist at SEOSiri. I focus on driving top SERP performance through technical skills and smart content strategy. Currently, I'm available for hire and looking for exciting consulting or full-time opportunities to make an impact. Interested in discussing how I can help? Let's chat on WhatsApp. You can also learn more about our work at SEOSiri.