title: Redirect TLD and 'blog' subdomain on github pages
body: <p>I started with GitHub Pages and I don't manage to configure my DNS and my GitHub Repository as I want to.</p>
  
  <p>I would like to redirect both <code>mydomain.com</code> and <code>blog.mydomain.com</code> to <code>username.github.com</code>.</p>
  
  <p>I put <code>mydomain.com</code> in the CNAME file in my GitHub repository and added A records for <code>@</code> to <code>204.232.175.78</code> and two CNAME records for <code>www</code> and <code>blog</code> to <code>username.github.com</code> the URL <code>blog.mydomain.com</code> give me a GitHub 404 error.</p>
  
  <p>What is wrong with my configuration?</p>