intermediate
Networking basics
Reason about TCP, UDP, DNS, TLS, IP addressing, ports, connection setup, latency, and common failure modes.
Networking basics interviews test TCP vs UDP, DNS resolution, TLS and certificates, and IP addressing with ports—foundations for debugging latency and connection failures.
Subtopics: TCP and UDP, DNS resolution, TLS and certificates, and IP addressing and ports.
On interviews: walk through a connection setup, explain why a service cannot bind a port, and describe common TLS handshake failure symptoms.
Common pitfalls: assuming UDP reliability, ignoring DNS TTL during migrations, and terminating TLS without understanding SNI and certificate chains.
The trade-off is balancing simplicity, performance, safety, and operability — name which axis you optimized and what cost you accepted.
Checklist:
- Compare TCP reliability with UDP use cases including QUIC.
- Explain recursive DNS, caching, and propagation delays.
- Know cert chains, termination points, and ALPN.
- Reason about ephemeral ports and NAT limits.