Articles & Guides
Useful resources for web developers and system administrators
HTTP
HTTP 502 Bad Gateway: What It Means and How to Fix
502 Bad Gateway decoded for nginx/Apache + PHP-FPM/Node.js, how it differs from 500/504, 7 causes, step-by-step fixes with config examples.
HTTP
HTTP 429 Too Many Requests: Rate Limiting Explained
HTTP 429 explained: how rate limiting works, nginx limit_req setup, Redis sliding window, proper Retry-After handling on clients and APIs.
HTTP
HTTP 403 Forbidden Error: 8 Ways to Fix
403 Forbidden causes and fixes: file permissions, .htaccess, nginx, WordPress, ModSecurity, IP blocks. Step-by-step diagnosis through server logs.
HTTP
HTTP 503 Service Unavailable: Causes and Solutions
HTTP 503 Service Unavailable explained: how it differs from 500/502, 6 causes and fixes for nginx, Apache, PHP-FPM, Kubernetes with config examples.
HTTP
HTTP 301 vs 302 Redirect: Differences and When to Use Each
301 vs 302 redirects compared: SEO impact, when to pick each, and setup examples for nginx, Apache, WordPress, PHP. Avoid common redirect mistakes.
HTTP
HTTP 500 Internal Server Error: What It Means and How to Fix
HTTP 500 Internal Server Error decoded: 8 common causes, how to read PHP, nginx, Apache and Node.js logs, and proven fixes for WordPress, Laravel, Express.
HTTP
HTTP 404 Not Found: RFC 9110 Definition, Causes and Fixes
What RFC 9110 §15.5.5 actually says about 404 Not Found: the exact wording, why a 404 is cacheable by default, how it differs from 410 and 403, plus fixes for nginx, Apache, Next.js and WordPress.
DNS
DNS Records: How to Add, Check and Fix Them — Enterno.io
A practical guide to DNS records: add and edit them in any panel, get TXT right (SPF, DKIM, DMARC), verify with dig, and diagnose failures by symptom.
SSL/TLS
How to Check SSL Certificate and Never Miss Expiration
How to check an SSL certificate: via browser, OpenSSL, and online tools. Certificate types, trust chain explained, and automated expiration monitoring.
Monitoring
Top 10 Website Monitoring Services 2026: Features and Pricing Compared
A comparison of 10 website monitoring services for 2026: an at-a-glance table (interval, Telegram, multi-region, price), a breakdown of each, and how to choose for your task.