Http/1.0

[coffeebean]

Sites hosted on shared IP accounts (that is, they rely on host headers) do not support HTTP/1.0 or HTTP/0.9, correct?

So are any pre-HTTP/1.1 browsers or other devices still in use?

[john_k]

Okay - since nobody else has chimed in yet, I will throw out what I think is the answer:

I believe that the "Host Headers" functionality utilizes the host name portion of the requested URL, so it is more of a server functionality issue and not dependant upon the browser. As long as the browser submits the full resource location, and does not use an IP, then there should be no problem. And, as long as your links use the host name instead of an IP, then that is what the browser will do.

Someone please correct this if it's wrong!

[coffeebean]

My understanding is the browser has to pass in the host header as part of the request in order for the server to map the correct virtual site. However the HTTP spec didn't suggest that browsers include the host header until version 1.1.

[DaveAtIFG]

That's my understanding as well coffeebean, but I'm not certain.

[john_k]

Dave & CoffeeBean - you are correct. I should have checked first. The RFC for HTTP 1.0 (RFC 1945) states that the host name is not required in the request line. So both of these would be valid request lines for the same resource:

GET /xyz.html HTTP/1.0
GET [example.com...] HTTP/1.0

Not that this answers your original question though.