HTTP/2 Compatibility with old Browsers and Servers

This post is a part 1 of HTTP/2 Complete Tutorial post series.

One of the biggest question that comes in is how is old browsers going to deal with HTTP/2 web servers and vice-versa.

HTTP/2 uses an Upgrade and Discovery method to find if a server supports HTTP/2 or not.

An HTTP/2 client never makes a HTTP/2 request by default. It always makes an HTTP/1.1 request with Upgrade: HTTP/2.0 header. If the web server is HTTP/2 capable then the server responds with HTTP/1.1 101 Switching Protocols status. But if the server is not capable of HTTP/2 then it simply returns an HTTP/1.1 response.

Clients usually remember whether the server supported HTTP/2 or not. And then the next time it makes an HTTP request it tries to make an HTTP/2 request directly instead of relying on upgrade round trip again.

Narayan Prusty
WordPress Multisite Database Table StructuresWhat is Multiplexing in HTTP/2?
Comments: 1
  1. Vic
    4 months ago

    You mention the client can remember if the server supports HTTP/2; where is this information stored in the browser? Is it by domain or IP address or something else?

    ReplyCancel

Leave a Reply

To create code blocks or other preformatted text, indent by four spaces:

    This will be displayed in a monospaced font. The first four
    spaces will be stripped off, but all other whitespace
    will be preserved.
    
    Markdown is turned off in code blocks:
     [This is not a link](http://example.com)

To create not a block, but an inline code span, use backticks:

Here is some inline `code`.

Narayan Prusty

Narayan is a web astronaut. He is the founder of QScutter and QNimate. Narayan is an expert in Web Development, Intel XDK, WordPress and Web Security. He is the main author of QNimate.

2 years ago 1 Comment Web Development
Share this
Related Articles