Network Fundamentals Part 2 Quiz — Transport and TLS
Last Updated: September 11, 2026
Tests your understanding of TCP, UDP, QUIC, and TLS.
Multiple Choice Questions
- How does QUIC avoid TCP’s cross-stream head-of-line (HOL) delivery dependency?
- A) Re-establish the entire connection on packet loss
- B) Maintain independent byte ordering for each stream within one connection
- C) Give up ordering guarantees entirely
- D) Handle retransmission at the kernel level
Show Answer
Answer: B) Maintain independent byte ordering for each stream within one connection
Explanation: TCP cannot deliver bytes beyond a missing segment, which can delay several HTTP/2 streams. QUIC can deliver available data from another stream independently. A stream can still wait for its own missing bytes; connection/path congestion control, packet recovery and application dependencies are shared concerns.
- Which statement about TLS 1.3 is NOT correct?
- A) A normal full handshake takes about 1 RTT; eligible resumption can carry optional 0-RTT early data
- B) RSA key exchange and weak cipher suites were removed
- C) TLS 1.3 alone encrypts SNI without ECH
- D) Ephemeral (EC)DHE provides forward secrecy, but PSK-only exchange and 0-RTT data have exceptions
Show Answer
Answer: C) TLS 1.3 alone encrypts SNI without ECH
Explanation: TLS 1.3 alone does not hide ClientHello SNI. ECH (RFC 9849) protects the inner ClientHello when supported and configured. TLS 1.3 permits PSK-only key exchange, and 0-RTT data lacks forward secrecy, so it is incorrect to describe forward secrecy as unconditional. Early data also does not mean that the handshake is already complete.
- What characterizes BBR’s approach to congestion control?
- A) Because it ignores packet loss and always sends at maximum speed
- B) It models bottleneck bandwidth and propagation RTT to guide sending, with loss/ECN behavior depending on the version
- C) Because it runs in user space instead of the kernel
- D) Because it delegates retransmission to the link layer
Show Answer
Answer: B) It models bottleneck bandwidth and propagation RTT to guide sending, with loss/ECN behavior depending on the version
Explanation: BBR uses a bandwidth/RTT model rather than relying only on a loss-driven congestion window. It still needs loss recovery and version-specific congestion responses. Performance depends on implementation, competing traffic and path conditions; higher throughput is not guaranteed.
- What rule must you follow when sending requests over TLS 1.3/QUIC 0-RTT session resumption?
- A) Send only POST requests
- B) 0-RTT data can be replayed, so allow only operations explicitly assessed as replay-safe by the application
- C) Certificate validation is skipped in 0-RTT, so use it only on internal networks
- D) 0-RTT only works over UDP, so block TCP fallback
Show Answer
Answer: B) 0-RTT data can be replayed, so allow only operations explicitly assessed as replay-safe by the application
Explanation: Early-data exchanges can be replayed and cause repeated application processing. A GET method name or a claim of idempotency alone is not proof of replay safety. Restrict early data to approved operations across the client/CDN/origin. An HTTP server can respond with 425 Too Early so the request is retried after the handshake.