A senior developer explains an API call: "The client sends an HTTP GET request, and the server responds with a JSON payload and a status code." What does HTTP stand for?
HTTP = HyperText Transfer Protocol. The foundation of data communication on the web. When your browser loads a page or an app calls an API, HTTP defines the format of requests and responses. Key HTTP concepts: Methods (GET, POST, PUT, PATCH, DELETE), Status codes (200 OK, 404 Not Found, 500 Internal Server Error), Headers (Content-Type, Authorization, Accept), Body (the request or response payload). HTTPS = HTTP + TLS encryption — the "S" stands for Secure. When you see a padlock in your browser, the connection uses HTTPS. Say it: "H-T-T-P" (letter by letter). Never say "H-T-T-P-S" as a word. In conversation: "What HTTP method does the endpoint use?", "Check the HTTPS certificate expiry."
2 / 5
During a backend review, a developer describes: "We use REST for our public API but internally we've switched to gRPC for service-to-service communication." What does REST stand for?
REST = Representational State Transfer. An architectural style for building web APIs defined by Roy Fielding in his 2000 dissertation. A REST API is "RESTful" when it follows key principles: (1) Stateless: each request contains all information needed — no session state on the server. (2) Resource-based: endpoints represent resources, not actions: GET /users/123 not GET /getUser?id=123. (3) HTTP methods have semantic meaning: GET (read), POST (create), PUT/PATCH (update), DELETE (remove). (4) Uniform interface: consistent structure across endpoints. Compare to SOAP (older, XML-based, stricter) and GraphQL (client queries exactly what data it needs). Say it: "REST" as a word (/rɛst/). "RESTful" is an adjective: "a RESTful API."
3 / 5
A developer debugging a network issue says: "The request times out — the DNS lookup is taking over 3 seconds." What does DNS stand for, and what does it do?
DNS = Domain Name System — the "phone book of the internet." When you type github.com, your device doesn't know the IP address. DNS resolves it: github.com → 140.82.121.3. Key concepts: DNS record types: A record (domain → IPv4), AAAA record (domain → IPv6), CNAME (alias), MX (mail server), TXT (verification, SPF). TTL (Time to Live): how long DNS results are cached — important for deployments. DNS propagation: after changing a DNS record, changes take time to spread globally (up to 48h, though usually faster). Common DNS issues: stale cache (flush with ipconfig /flushdns on Windows), misconfigured A records, SSL mismatch. Say it: "D-N-S" (letter by letter). "DNS lookup", "DNS resolution", "DNS provider" (Cloudflare, Route 53).
4 / 5
A DevOps engineer sets up secure communications: "We're terminating TLS at the load balancer — backend services communicate over plain TCP internally." What is the difference between TLS and TCP?
TCP = Transmission Control Protocol. The transport layer protocol that ensures reliable, ordered delivery of data. It handles: connection setup (3-way handshake: SYN → SYN-ACK → ACK), packet ordering, retransmission of lost packets, congestion control. Compare with UDP (User Datagram Protocol) — faster but no delivery guarantees, used for streaming, DNS queries, gaming. TLS = Transport Layer Security (successor to SSL). A cryptographic protocol that runs on top of TCP and adds: authentication (via certificates), encryption, and data integrity. HTTPS = HTTP + TLS over TCP. "TLS termination" at the load balancer means it decrypts traffic there, so internal services don't need to handle encryption. Say: "T-L-S", "T-C-P" (letter by letter). Old term: SSL (Secure Sockets Layer) — mostly deprecated but still used informally ("SSL certificate").
5 / 5
A security engineer advises: "Never expose internal services directly — put everything behind a VPN and use SSH for remote access." What do VPN and SSH stand for?
VPN = Virtual Private Network. Encrypts your internet traffic and routes it through a server, masking your IP and securing the connection. In enterprise: employees connect to the company VPN to access internal systems (staging servers, internal tools, private APIs) as if they were in the office. Protocols: OpenVPN, WireGuard, IPSec. Say it: "V-P-N" (letter by letter). SSH = Secure Shell. A cryptographic protocol for secure remote login and command execution on servers. Replace the old Telnet protocol (which sent passwords in plain text). Key SSH concepts: key pair (private key on your machine, public key on the server), ssh-keygen (generates key pairs), ~/.ssh/authorized_keys (stores public keys on the server). Say it: "S-S-H" (letter by letter). Common usage: "SSH into the server", "Generate an SSH key", "Add your SSH key to GitHub."