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http-concepts.md

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copyright lastupdated keywords subcollection
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2020, 2024
2024-11-07
cis

{{site.data.keyword.attribute-definition-list}}

HTTP concepts

{: #http-concepts}

HTTP/2 and HTTP/3 accelerate page load and are included in all {{site.data.keyword.cis_full}} plans. HTTP/2 is enabled by default and requires an SSL certificate at the {{site.data.keyword.cis_short_notm}} edge network. Domains on Trial plans cannot disable HTTP/2. {: shortdesc}

A browser and web server automatically negotiate the highest protocol available, so HTTP/3 takes precedence over HTTP/2. {{site.data.keyword.cis_short_notm}} only uses HTTP/1.x between the origin web server and {{site.data.keyword.cis_short_notm}}.

To determine the protocol used for your connection, enter example.com/cdn-cgi/trace from a web browser or client and replace example.com with your domain name. If http=h2 appears in the results that are returned, the connection occurred over HTTP/2. Other possible values are http=http2+quic/99 for HTTP/3, and http=http/1.x for HTTP/1.x.

HTTP/2

{: #http-2}

HTTP/2 improves page load times through:

  • Connection multiplexing - Retrieves multiple resources in a single network request. Responses are sent when resources are available to avoid slowing page rendering.
  • HTTP header compression - Compresses headers and simplifies HTTP requests to avoid resending headers.
  • HTTP/2 Server Push - To improve page load speed, {{site.data.keyword.cis_short_notm}} provides additional resources for a client to cache without waiting for additional requests.

Not all browsers support HTTP/2 and use HTTP 1.x instead. Connection multiplexing is on a per-domain basis. {: note}

HTTP/3

{: #http-3}

HTTP/3 enables fast, reliable, and secure connections. HTTP/3 encrypts internet transport by default using a protocol from Google called QUIC. Enable HTTP/3 via the Cloudflare Network app. Use the following methods to experiment with HTTP/3.

Using Google Chrome as your HTTP/3 client

{: #chrome-client}

To use Chrome to connect to your website over HTTP/3, first download and install the latest Canary build{: external}. Then, enable HTTP/3 support in Chrome Canary using the --enable-quic and --quic-version=h3-23 command-line arguments{: external}.

After Chrome starts, type your domain in the address bar. Check the protocol version using the Network tab in Chrome’s Developer Tools. If http2+quic/99 doesn’t appear in the Protocol column when connecting to your domain, try reloading the page.

Using cURL

{: #using-curl}

The cURL command-line tool supports HTTP/3. Download the latest version{: external} and follow the instructions to enable HTTP/3 support{: external}.

For macOS, use Homebrew to install cURL with HTTP/3 support:

brew install --HEAD -s https://raw.githubusercontent.com/cloudflare/homebrew-cloudflare/master/curl.rb

{: pre}

Then, perform an HTTP/3 cURL with the --http3 command-line flag:

./curl -I https://blog.cloudflare.com/ --http3

{: pre}

Confirm HTTP/3 appears in the response and that there were no error messages.