CNAME

对于 https://a.xiezhao.me cname https://b.xiezhao.me
如果要SSL访问. a.xiezhao.me 和 b.xiezhao.me都需要SSL certificate
A CNAME is not a redirect.
A CNAME instructs the DNS to resolve to the same domain as where the CNAME points.
The CNAME does not cause a redirect.
It only causes the HTTP request for a domain to be made to the same IP address as requests for another domain.

cname https://site1.example/ to https://site2.example/

1. DNS lookup for site1.example. Discover it it is a CNAME for site2.example.
2. DNS lookup for site2.example. Find an A record for its IP address (192.0.2.4, for example).
3. Open a socket to the IP address 192.0.2.4 on port 443.
4. Negotiate TLS (SSL) for the domain site1.example.
5. Make the HTTPS request for https://site1.example/: shell GET / HTTP/1.1 Host: site1.example 6. Get the response back with the redirect: shell 301 Moved Permanently Location: https://site2.example/
6. Perform another DNS lookup for site2.example. Find an A record for its IP address (192.0.2.4, for example). The DNS response will come from DNS cache this time.
7. Open a socket to the IP address 192.0.2.4 on port 443.
8. Negotiate TLS (SSL) for the domain site2.example.
9. Make the HTTPS request for https://site2.example/: shell GET / HTTP/1.1 Host: site2.example 11. Get the response back with the content: shell 200 OK ...