ASP.NET Core Interview Question #189

What is HTTP/3?

Performance, Caching & HTTP Senior Advanced

Quick Interview Answer

HTTP/3 carries HTTP semantics over QUIC rather than TCP. QUIC uses UDP as its transport and integrates modern encryption and stream multiplexing.

Detailed Explanation

HTTP/3 carries HTTP semantics over QUIC rather than TCP. QUIC uses UDP as its transport and integrates modern encryption and stream multiplexing.

A major benefit is that packet loss affecting one stream does not create the same cross-stream TCP head-of-line blocking behavior. HTTP/3 can also improve connection establishment in supported scenarios.

Actual use depends on operating system, server, proxy, TLS, client, and network support; applications should not assume every request uses HTTP/3.

Code Example

// Applications normally continue using ordinary
// ASP.NET Core endpoints. Protocol negotiation is
// handled by the server/hosting configuration.
app.MapGet("/", () => "Hello");