Articles & Guides
Useful resources for web developers and system administrators
Networking
Cloudflare in Russia 2026: Blocks, Risks, and What Site Owners Should Do
Cloudflare in Russia 2026: is Cloudflare blocked in Russia, why sites behind Cloudflare fail to load from Russian networks (TLS ECH), the risks for owners with Russian audiences, local CDN alternatives, and a step-by-step migration plan with DNS and SSL checks.
Infrastructure
Email Not Arriving: A Checklist for Senders and Recipients
Email not arriving? A step-by-step checklist for senders and recipients: Spam folder, SPF, DKIM, DMARC, MX records, blacklists, bounce codes 550, 552, 554, greylisting. Includes a symptom-cause-fix table, dig commands, and answers to common questions.
DNS
How to Check a Domain's MX Record
How to check a domain's MX record: a DNS check or dig, what the priorities and an empty answer mean, common mail problems and the link to SPF/DKIM/DMARC.
Security
How to Check a Website for 152-FZ Compliance: An Owner's Checklist
A self-check checklist for a website's 152-FZ compliance: policy, voluntary consent, cookie notice, data storage in Russia, Roskomnadzor notice, HTTPS.
SSL/TLS
"Cannot Verify Server Certificate": What It Means and How to Fix It
What the "cannot verify the server certificate/identity" error means and how to fix it: name mismatch, expiry, self-signed, incomplete chain, revocation.
Security
Content-Security-Policy Blocked a Script: How to Read and Fix CSP Errors
How to read a CSP console error and fix it correctly: the script-src/connect-src directives, nonce and hash instead of unsafe-inline, and Report-Only mode.
DNS
How to Connect a Domain to Hosting: Step by Step
Two ways to connect a domain to hosting: change the NS servers or add an A record. Step by step, how long DNS takes to update, and how to confirm it worked.
Monitoring
How to Check a Website for Errors: A Technical Checklist
How to check a site for technical errors by category: broken links, 5xx, mixed content, browser console, headers. What to check each with and in what order.
HTTP
How to Check a Site's Redirects: The Redirect Chain in a Minute
How to check a redirect chain and a link’s final address: a tool, curl, DevTools. What 301/302/307/308 mean and which chains are dangerous.
Security
DDoS Protection: How to Defend Your Site Before an Attack
The layers of DDoS protection: filtering proxy/CDN, WAF, rate limiting, hidden IP, capacity headroom. How defense differs for volumetric vs application attacks.