You now have the networking fundamentals needed for SRE interviews.
Key concepts:
- TCP: reliable, three-way handshake, congestion control
- UDP: unreliable but faster, good for DNS and streaming
- DNS: hierarchical resolution, record types (A, CNAME, MX)
- HTTP/HTTPS: request/response, status codes, TLS encryption
- Load balancing: L4 (transport) vs L7 (application)
Key tools: ping, telnet, curl, dig, tcpdump, netstat/ss
Debugging approach: Start at the application layer and work down. Verify DNS, then connectivity, then firewall rules.