Developer Reference
Look up developer standards, protocol facts, limits, and sources for code, data, network, and web tasks.
HTTP Status Codes
Every common status code, what it means, and what to check when 502/503/504 hit.
Network Ports
The ports you actually meet — services, ranges, and security notes.
Unix Permissions
rwx, octal modes, and what 755 vs 644 vs 600 really allow.
Sources and verification
Definitions are checked against public standards and maintained technical documentation. The links are there so you can verify the facts behind each quick answer.