Computer Networks learning guides

Understand how the internet moves information from one computer to another.

Articles in Computer Networks

  • What Happens When You Type a URL? — Follow a web request from the address bar through DNS, the network, and the browser as a page appears on your screen. 5 min read · 2026-10-23
  • DNS: The Internet's Address Book — Learn how domain names become IP addresses and how DNS resolvers find answers efficiently. 5 min read · 2026-10-22
  • HTTP Requests and Responses, Explained — Understand methods, status codes, headers, and the request-response cycle behind websites and APIs. 5 min read · 2026-10-21
  • TCP vs. UDP: Choosing How Data Travels — Compare reliable, ordered delivery with lightweight datagrams and see where each transport fits. 5 min read · 2026-10-20
  • TLS and HTTPS: Securing a Web Connection — See how certificates and encryption help browsers communicate privately with the right server. 6 min read · 2026-10-19
  • HTTP Caching and CDNs: Serving Pages Closer and Faster — Understand browser and shared caches, freshness rules, validators, and how a CDN reduces latency without serving stale content. 7 min read · 2026-10-28
  • The TCP/IP Layers and Encapsulation — Network layers divide communication responsibilities, and each layer wraps data with metadata needed by the next one. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • IPv4 Addresses and Network Prefixes — An IPv4 prefix separates network bits from host bits so routers can group destinations by shared address ranges. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Subnet Masks and Address Capacity — A subnet mask marks which IP address bits identify a network and which identify hosts. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • ARP and Finding a Neighbor on a Local Network — Address Resolution Protocol maps a local IPv4 address to a link-layer address needed to send a frame on the local network. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • DHCP and Automatic Network Configuration — Dynamic Host Configuration Protocol leases network settings such as an address, gateway, and DNS resolver to a client. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Routing Tables and Next-Hop Decisions — A routing table maps destination prefixes to next hops or interfaces, allowing each router to forward one packet at a time. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • The TCP Three-Way Handshake — TCP establishes a connection by exchanging SYN, SYN-ACK, and ACK segments that synchronize sequence state in both directions. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • TCP Sequence and Acknowledgment Numbers — TCP sequence numbers identify byte positions in a stream, while acknowledgments report the next expected byte. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • TCP Congestion Control and the Sending Window — TCP adjusts its sending rate in response to network feedback to avoid overwhelming shared paths. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • UDP Datagrams and Application-Level Reliability — UDP sends independent datagrams without TCP's built-in delivery, ordering, or retransmission guarantees. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • DNS Caching, TTLs, and Resolver Behavior — DNS resolvers cache records for their time-to-live so repeated name lookups can avoid another full hierarchy traversal. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • TLS Certificates and Domain Validation — TLS certificates bind a public key to a domain identity through a chain that clients validate against trusted roots. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • HTTP Methods and Their Intended Semantics — HTTP methods communicate the intended operation, such as retrieving a representation or submitting a change. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • HTTP Status Codes and Response Categories — HTTP status codes summarize whether a request succeeded, needs more action, or encountered a client or server problem. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • HTTP Headers and Negotiating Representations — HTTP headers carry metadata about requests and responses, including content type, caching policy, and accepted formats. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • REST Resources and Stateless Request Design — REST-style APIs expose resources through consistent identifiers and HTTP operations while keeping each request self-contained. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • WebSockets and Persistent Bidirectional Messages — WebSockets upgrade an HTTP connection into a persistent channel that supports messages in both directions. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Load Balancing Across Application Instances — A load balancer distributes requests across healthy service instances using a routing policy. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Rate Limiting and Token-Bucket Behavior — Rate limiting constrains request volume, and a token bucket allows short bursts while limiting the long-term average. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Exponential Backoff and Jitter for Retries — Exponential backoff increases delay between retries, while jitter randomizes timing to avoid clients retrying in lockstep. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Eventual Consistency Across Replicas — Eventual consistency permits replicas to temporarily disagree while promising convergence after updates stop propagating. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Content Delivery Networks and Edge Caching — A CDN serves cacheable content from edge locations closer to users, reducing origin work and network distance. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • HTTP/3 and QUIC Connection Setup — HTTP/3 carries HTTP semantics over QUIC, which uses UDP while implementing transport features including encryption and stream multiplexing. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Cookies, Sessions, and Browser Request State — Cookies let a server ask a browser to send small pieces of state with matching future requests. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29
  • Polling, Server-Sent Events, and WebSockets — Applications can receive updates by periodic polling, one-way server-sent events, or bidirectional WebSocket messaging. This guide works through a concrete example and the trade-offs to remember. 2 min read · 2026-10-29