Hosting a github page site to subdomain of a domain

-Host the website the same way as above and add the CNAME file containing the domain with subdomain i.e

blog.google.com here blog is the subdomain of google

-In the dns settings of the custom domain add a CNAME record

Type	Host	Value	TTL
CNAME(ALIAS)	blog.google.com	userName.github.io.	Automatic