Guides

Learn how website downtime works

Technical deep-dives on outages, DNS failures, HTTP errors, CDN issues, and how to diagnose any website problem from first principles.

Is a website down for everyone or just me?

How to tell whether a site is globally unreachable or whether your local network, ISP, or DNS cache is the problem.

What every 4xx and 5xx status code means, why it happens, and exactly how to fix it — from 404 to 503.

The full DNS lookup chain explained — and why a single broken record can take your entire site offline in minutes.

How uptime percentages are calculated, what 99.9% SLA actually means in minutes of downtime per year, and how to measure it.

Response time thresholds explained — TTFB, page load time, and what causes a site to be slow vs unreachable.

How Content Delivery Networks distribute your site globally, and why a CDN failure can cause regional outages even when your server is fine.

The best free tools to track whether your site stays online 24/7 and get instant alerts when it goes down.

Every browser SSL error explained — from expired certificates to mixed content, and step-by-step fixes for each.

How distributed denial-of-service attacks overwhelm servers, what a DDoS looks like from a monitoring perspective, and how sites defend against them.

How major cloud outages cascade across millions of sites, why AWS us-east-1 failures make headlines, and how to check if a provider is down.

How to diagnose whether your ISP or government is blocking a site versus it actually being down — and your options for bypassing the block.