--- title: Blog — page 4 of 7 description: Practical guides on monitoring, reliability, and performance — plus product news and lessons from the WatchFor team. canonical: https://watchfor.io/blog/page/4 --- # What we watch for — page 4 Practical guides on monitoring, reliability, and performance — plus product news and lessons from keeping our own systems online. [All](/blog)[Monitoring](/blog/category/monitoring)[Networking](/blog/category/networking)[Performance](/blog/category/performance)[Security](/blog/category/security)[Reliability](/blog/category/reliability)[Email](/blog/category/email)[DevOps](/blog/category/devops)[Engineering](/blog/category/engineering) [All articles](/blog/all) 136 article s · page 4 of 7 [MonitoringApr 18, 2026 ## Webhooks 101: what they are and how to use them A webhook is how one app says 'hey, this just happened' to another — instantly, without anyone asking. Here's what webhooks are, how they differ from polling, and how to use them well.WatchFor Team3 min read](/blog/webhooks-101)[NetworkingApr 15, 2026 ## 503 Service Unavailable: what it means and how to fix it A 503 means your server is alive but can't handle the request right now — usually overload or maintenance. Here's what's happening, how to fix it, and how to keep it from surprising your users.WatchFor Team3 min read](/blog/503-service-unavailable)[NetworkingApr 11, 2026 ## 504 Gateway Timeout: what it means and how to fix it A 504 means a proxy waited for your app to respond — and gave up. It's the signature of something slow, not something dead. Here's how to find the slowness and fix it.WatchFor Team3 min read](/blog/504-gateway-timeout)[PerformanceApr 08, 2026 ## What is a CDN? (And do you actually need one?) A CDN makes your site faster by serving it from locations close to your users. Here's how that works, what you actually gain, and whether your site needs one.WatchFor Team3 min read](/blog/what-is-a-cdn)[NetworkingApr 04, 2026 ## TCP vs UDP: the difference, explained simply Two protocols carry almost everything on the internet. TCP is the careful courier; UDP is the fast one that doesn't look back. Here's how they differ and when each is the right choice.WatchFor Team3 min read](/blog/tcp-vs-udp)[MonitoringApr 01, 2026 ## Rate Limiting & HTTP 429 Explained Rate limiting is how services protect themselves from too many requests — and HTTP 429 is how they say 'slow down'. Here's how it works, and how to handle it gracefully on both sides.WatchFor Team3 min read](/blog/rate-limiting-explained)[NetworkingMar 28, 2026 ## IPv4 vs IPv6: what's the difference (and why IPv6 exists)? Every device online needs an address — and we ran out of the old kind. Here's the difference between IPv4 and IPv6, why the switch is happening, and whether you need to care.WatchFor Team3 min read](/blog/ipv4-vs-ipv6)[EmailMar 25, 2026 ## Email Blacklists (RBLs): why you're blocked and how to get off If your email suddenly stops arriving, a blacklist may be the culprit. Here's what RBLs are, how you end up on one, and the step-by-step to get off — and stay off.WatchFor Team3 min read](/blog/email-blacklists-rbl)[ReliabilityMar 21, 2026 ## Disaster Recovery: RTO vs RPO explained When the worst happens, two numbers decide how bad it really is: how much data you lose, and how long you're down. Here's what RTO and RPO mean, and how to set targets you can actually meet.WatchFor Team3 min read](/blog/disaster-recovery-rto-rpo)[ReliabilityMar 18, 2026 ## What is SRE? Site Reliability Engineering, explained SRE is what you get when you treat reliability as an engineering problem instead of a firefighting one. Here's what Site Reliability Engineering actually means, its core ideas, and how it differs from DevOps.WatchFor Team3 min read](/blog/what-is-sre)[PerformanceMar 14, 2026 ## What is TTFB (Time to First Byte) and how to improve it TTFB is the first number that tells you whether your backend is fast or slow. Here's what Time to First Byte measures, what's 'good', what makes it bad, and how to bring it down.WatchFor Team3 min read](/blog/ttfb-explained)[NetworkingMar 12, 2026 ## 404 Not Found: what it means and how to handle it 404 is the internet's most famous error — and unlike most, it's often nobody's emergency. Here's what it means, when it's fine, when it isn't, and how to handle it well.WatchFor Team3 min read](/blog/404-not-found)[NetworkingMar 10, 2026 ## 403 Forbidden: causes and how to fix it A 403 means the server understood you perfectly — and is refusing anyway. Here's what causes 'Forbidden', how it differs from 401, and how to track down the fix.WatchFor Team2 min read](/blog/403-forbidden)[NetworkingMar 08, 2026 ## 401 vs 403: Unauthorized vs Forbidden 401 and 403 are the two 'you can't have this' codes — and they're constantly confused. Here's the simple rule for telling them apart, with examples.WatchFor Team3 min read](/blog/401-vs-403)[NetworkingMar 06, 2026 ## 500 Internal Server Error: what it means and how to fix it 500 is the server's way of saying 'something went wrong and I don't know how to explain it.' Here's what causes it, how to find the real error, and how to stop it recurring.WatchFor Team3 min read](/blog/500-internal-server-error)[NetworkingMar 04, 2026 ## 301 vs 302 Redirects: which one should you use? Both send visitors from one URL to another — but to search engines they mean very different things. Use the wrong one and you can quietly tank your SEO. Here's the difference.WatchFor Team3 min read](/blog/301-vs-302-redirects)[MonitoringMar 02, 2026 ## CORS Errors Explained (and how to fix them) Every web developer meets the dreaded 'blocked by CORS policy' error. It's not a bug — it's a security feature. Here's what CORS is, why the browser blocks your request, and how to fix it properly.WatchFor Team3 min read](/blog/cors-errors-explained)[PerformanceFeb 28, 2026 ## ERR_TOO_MANY_REDIRECTS: causes and how to fix it When a page keeps redirecting to itself, the browser gives up with 'too many redirects'. Here's why redirect loops happen and the usual culprits behind them.WatchFor Team3 min read](/blog/too-many-redirects)[SecurityFeb 26, 2026 ## SSL/TLS Handshake Failed: causes and how to fix it When the secure connection can't be agreed, you get a handshake failure — and the page never loads. Here's what goes wrong during the TLS handshake, and how to fix each cause.WatchFor Team3 min read](/blog/ssl-handshake-failed)[SecurityFeb 24, 2026 ## Mixed Content Warnings: what they are and how to fix them Your site is on HTTPS, but the padlock has a warning — or images won't load. That's mixed content: a secure page pulling in insecure resources. Here's how to find and fix it.WatchFor Team3 min read](/blog/mixed-content-warnings) --- Canonical page: https://watchfor.io/blog/page/4 · Site guide: https://watchfor.io/llms.txt