Google uses HTTP/3 (QUIC over UDP) so mobile phone users switching from Wi-Fi to 5G cellular networks maintain persistent connection state without re-negotiating TCP/TLS handshakes.
Visual representation of control loops, memory layout, and execution flow for HTTP/1.1 vs HTTP/2 vs HTTP/3 (QUIC) & HTTPS.
Text-based protocol; suffers from Head-of-Line blocking (1 request per TCP connection).
Adds TLS handshake encrypting symmetric keys using RSA/Elliptic Curve Diffie-Hellman.
Introduces binary framing, multiplexing multiple streams over 1 TCP connection, and HPACK header compression.
Runs over UDP; eliminates TCP Head-of-Line blocking and enables zero RTT connection resumption.
| Feature / Dimension | HTTP/2 | HTTP/3 |
|---|---|---|
| Transport Protocol | Runs on top of TCP | Runs on top of UDP (using QUIC) |
| Head-of-Line Blocking | Suffers from TCP HOL blocking if packet is lost | Eliminates HOL blocking completely at transport layer |
| Connection Resumption | Requires new TCP + TLS negotiation on IP change | Uses 64-bit Connection ID allowing seamless network roaming |
Detailed answers, interviewer pro tips, key takeaway summaries, and code examples formulated for technical rounds.
✅ Correction: HTTPS encrypts Application Layer payloads and HTTP headers; IP addresses and TCP port numbers remain visible to routers.
Application protocols for Web content delivery.