Can browsers load two components in parallel on a subdomain?

Question

I know that: "browsers can load two components in parallel to the host name example www.example.com and www.example.org

My question is: can browsers load two components in parallel on a subdomain? www.example.com and images.example.com

Answer 1

Yes, they can. I just did this with a Ruby on Rails application, using native Rails support for multiple resource hosts. They are all subdomains, for example. asset0.example.com, asset1.example.com etc.

Answer 2

The rule is actually weaker, "no need to load more than 2". And yes, this is the host name. www.example.com and images.example.com are two host names. However, there is no guarantee that browsers will actually use 4 simultaneous downloads.