OSI Model
The OSI model's seven layers give engineers a shared vocabulary for exactly where a network problem lives, and why TCP/IP doesn't map onto it cleanly.
IP Addresses
IP addresses identify devices and route traffic. Covers IPv4 vs IPv6, public vs private ranges, NAT, and why a stable address matters for DNS.
DNS
DNS translates domain names into IP addresses through a caching hierarchy. Covers TTL tradeoffs and how DNS doubles as a load balancing tool.
Proxy vs Reverse Proxy
A forward proxy hides the client; a reverse proxy hides the servers. One question — whose identity is hidden from whom — tells them apart instantly.
HTTP/HTTPS
HTTP is a stateless request/response protocol; HTTPS wraps it in TLS encryption. Covers the handshake cost and the jump from HTTP/1.1 to HTTP/3.
TCP vs UDP
TCP guarantees ordered, reliable delivery; UDP trades that away for speed. Covers why video calls and DNS queries deliberately choose UDP anyway.
Load Balancing
A load balancer spreads requests across servers so none gets overwhelmed. Covers Layer 4 vs Layer 7 routing and the algorithms that pick a server.
Checksums
A checksum catches accidental data corruption cheaply, and it's not the same tool as a cryptographic hash. Here's when to reach for each one.