Articles & Guides
Useful resources for web developers and system administrators
DNS
SPF Record Explained: Syntax and -all
SPF record explained: v=spf1 syntax, include, a, mx, ip4 mechanisms and the ~all vs -all difference. Example records, dig commands and common SPF mistakes.
Security
How to Get Off an Email Blacklist
How to check and get off an email blacklist: Spamhaus, Barracuda, SpamCop. dig commands for DNSBL, listing causes and the step-by-step delisting process.
Security
Emails Going to Spam: Causes and Fix
Why your emails land in spam and how to fix it: SPF, DKIM, DMARC, IP reputation, content and blacklists. Step-by-step domain diagnosis and DNS record checks.
Monitoring
Diagnosing Intermittent Downtime
Site goes down intermittently and you can't catch it? How to diagnose flaky outages: continuous monitoring, multi-region checks, a health-check script, and API.
Monitoring
Website Slow to Load: Causes and Fix
Website slow to load? Break it down by phase: DNS, TCP, TTFB, render. Use curl to measure each phase, then a list of causes and fixes to speed your site up.
Monitoring
Website Not Loading: Why It Happens and a 10-Step Fix Checklist
Website not loading? Read the browser error, find the failing layer (device, DNS, TLS or server) and fix it with exact commands for visitors and site owners.
Monitoring
Cloudflare Error 1020 Access Denied Fix
Cloudflare Error 1020 Access Denied means a WAF or Firewall Rule blocked the request. How to find the triggered rule, read the logs, and remove the block.
SSL/TLS
Cloudflare 525 SSL Handshake Failed Fix
Cloudflare error 525 SSL Handshake Failed means the TLS handshake with the origin failed. Check the origin certificate, use openssl s_client, and fix SSL modes.
HTTP
Cloudflare Error 522 Connection Timed Out: How to Fix
Cloudflare 522: the TCP connection to your origin timed out. Check the origin is up, allow Cloudflare IPs in the firewall, verify the A record, use curl.
DNS
DNS_PROBE_FINISHED_NXDOMAIN: Fix It in Chrome, Mac and Android
DNS_PROBE_FINISHED_NXDOMAIN means the name did not resolve. Fix it in Chrome, Edge, Mac and Android: cache flush, secure DNS, dig checks and owner-side fixes.