This is from the section 3.3.1 of SPDY Protocol - Draft 2 [0]: "When a server receives a non-SPDY request which could have been served via SPDY, it should appe

This is from the section 3.3.1 of SPDY Protocol - Draft 2 [0]: "When a server receives a non-SPDY request which could have been served via SPDY, it should append a Alternate-Protocol header into the response stream. Note that it is valid to have multiple Alternate-Protocols headers. The field-value can also be specified as a comma-separated list, as per RFC2616 section 4.2." And you can read about "deferred" here: https://stackoverflow.com/questions/8449058/what-does-the-deferred-option-mean-in-nginxs-listen-directive https://stackoverflow.com/questions/8449058/what-does-the-de... [0] - http://dev.chromium.org/spdy/spdy-protocol/spdy-protocol-draft2 http://dev.chromium.org/spdy/spdy-protocol/spdy-protocol-dra...