Debugging
6 posts tagged with Debugging.
What `429 Too Many Requests` actually means, and how rate limits really work
Most rate-limit explanations stop at 'you went too fast.' That's true but not useful. Real rate limiters work in five different ways — token bucket, leaky bucket, fixed window, sliding window, concurrency cap — and the headers tell you which one you're hitting, when to retry, and how much budget you have left.
Why your DNS change isn't propagating: the five timers that actually govern it
'DNS propagation' has nothing to do with how long it takes. There is no single timer. There are five separate caches between your registrar and your visitors' resolvers — and you need to understand all of them to predict the answer to 'when will the new record be live?'
Permanently shut down or just down right now? A 10-minute diagnosis
A site won't load. Is it a five-minute hiccup, an outage that ends today, or has the service quietly been dead for two years? The diagnostic isn't intuition — it's six concrete signals, in priority order. Here is the workflow we run.
Reading SSL certificate errors: the four most common ones, decoded
ERR_CERT_AUTHORITY_INVALID. NET::ERR_CERT_DATE_INVALID. ERR_CERT_COMMON_NAME_INVALID. ERR_SSL_VERSION_OR_CIPHER_MISMATCH. The browser tells you almost exactly what's wrong if you know how to read it. Here is what each one means, why it happens, and what to do.
The 5xx family: 500 / 502 / 503 / 504 / 520 and what each one is actually telling you
Every 5xx code is a server's way of saying 'something went wrong on our end.' But they are not interchangeable. 502 means upstream; 504 means upstream-but-slow; 503 means deliberately unavailable; 520 means Cloudflare-doesn't-know. Knowing which one you got cuts the bug-hunt by more than half.
Reading an HTTP redirect chain — the underrated debugging skill
When 'is the site down' turns out to be 'the site is fine, but the redirect chain is sending users somewhere unexpected,' the only useful diagnostic is the full hop-by-hop trail. Here's what each step tells you, and the patterns that crop up most often.