DNS changes
When changing host records, lower TTL before migration, verify from more than one resolver, and keep old endpoints online during propagation.
Field notes
Notes
Compact reminders for common operational checks and web engineering tasks.
HTTP status classes
Use 2xx for success, 3xx for redirects, 4xx for client-side request issues, and 5xx when the server failed to complete a valid request.
Release checklist
Before a small release, confirm backups, expected ports, service status, logs, rollback command, and one real user journey.
Network troubleshooting
Separate local device issues from route issues: test DNS resolution, TCP or UDP reachability, packet loss, and one known-good endpoint.