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