自定义域名无法跳转至GitHub Pages，已尝试三步配置仍未解决

Let’s work through this problem step by step—custom domain setups for GitHub Pages often have small, easy-to-miss details that can cause this kind of stuck behavior. Here are the key checks to run:

1. Verify GitHub Repository Pages Settings #

• Head to your repository’s Settings > Pages section:
  • Make sure the Custom domain field is explicitly set to mydomain.com (don’t just rely on the CNAME file alone—sometimes GitHub fails to auto-detect it properly).
  • If HTTPS is available for your domain, check the Enforce HTTPS box (this helps with redirect consistency once everything propagates).
• Double-check your repository’s CNAME file:
  • Ensure it’s in the root directory (or docs folder if you’re using that as your Pages source) with only the text mydomain.com—no extra spaces, line breaks, or formatting.

2. Validate DNS Records Propagation #

• Use terminal commands to confirm your domain is resolving correctly:
  • Run dig mydomain.com A—you should see both 192.30.252.153 and 192.30.252.154 in the output.
  • Run dig www.mydomain.com CNAME—the result should point directly to username.github.io.
• Remember: DNS changes can take 24-48 hours to fully propagate across global servers. Even if your local machine shows the correct records, other regions might still be using old data.
• Log into your domain.com account and check for conflicting records: Make sure there are no leftover A/CNAME records for mydomain.com or www.mydomain.com that might override your new settings.

3. Rule Out Browser/Network Caching #

• Clear your browser’s cache and cookies, then try accessing both mydomain.com and username.github.io in incognito/private mode. Old cached redirects can stick around even after your settings are correct.
• Test with a different network (e.g., mobile hotspot) to bypass your local DNS cache, which might still be serving outdated records.

4. Trigger a Fresh GitHub Pages Deployment #

• Sometimes GitHub’s Pages cache can hold onto old configurations. To force a refresh:
  • Make a tiny edit to any file in your repository (e.g., add a space to your README.md).
  • Commit and push the change—this will trigger a new deployment, which often resolves stuck redirects or configuration issues.

5. Check for GitHub Pages Service Issues #

• Occasional outages or delays with GitHub Pages can cause unexpected behavior. You can check GitHub’s official status page to confirm the service is operating normally.

If you’ve gone through all these steps and still see the default landing page, check the bottom of your repository’s Settings > Pages page—GitHub will sometimes display specific error messages (like domain verification failures or mismatched records) that can point you to the exact problem.

内容的提问来源于stack exchange，提问作者user8094057