Free egress is not free serving. R2 still bills every read, S3 does not bill origin transfer to CloudFront, and the variable that decides both bills is cache hit ratio. An evenhanded comparison of Cloudflare R2 vs Amazon S3 for media offloading, with the four levers that move the number and a decision procedure you can run against your own traffic.
Sending works, nothing comes in, and no bounce shows up anywhere. That asymmetry tells you almost everything: inbound mail is decided by MX records, not by SPF. This guide walks the inbound path in the order a sending server actually walks it, groups the real causes into five DNS failure families, and gives you the dig commands to prove which one you are looking at.
A limit_req block that parses cleanly can still be doing absolutely nothing, or throttling every visitor behind one CDN edge. This guide covers Nginx rate limiting and bot mitigation as they actually behave in production: getting the key right behind a proxy, what burst and nodelay do to your traffic shape, sizing zones correctly, rolling out in dry run mode, and layering bot handling from robots.txt through user agent maps to firewall escalation.
Third-party API spend is the one production signal with no error rate attached to it, which is why it creeps up quietly. This is a working engineer's guide to reducing SaaS API costs by changing the shape of your calls: reading the billing unit before you optimise anything, killing pointless polling with conditional requests and webhooks, collapsing N+1 patterns, caching with stampede protection and per-tenant keys, stopping your own retry amplification, and attributing spend so you can prove the work paid off.
Managed WordPress hosting and a self-managed VPS can both serve a fast site. They differ on which failures land on you. A practical comparison covering visit metering, disallowed plugin policies, silent backup failure, patching debt, and a cost model that survives contact with reality.
You got PageSpeed Insights to 98 and six weeks later Search Console still says the same URLs are failing. The score and the assessment measure different things, and Lighthouse cannot measure INP at all. Here is how to fix Core Web Vitals on WordPress in the order that actually moves the report.
Your browser shows a padlock and your partner's API client throws "unable to get local issuer certificate". Both are correct. A practical guide to the four things a TLS client actually checks, and to renewal automation that reaches the running server instead of just the disk.
Put a CDN in front of a dynamic site carelessly and it will cache one user's personalised page and serve it to everyone — invisibly, because your logged-in browser looks fine. Here is how to classify routes, set cache headers that hold, and run the two curl commands that catch the leak.
Almost every TLS certificate error traces back to one of three causes: a broken chain, a hostname the certificate does not cover, or an expiry nobody was watching. Here is how to tell them apart in under a minute, and how to stop the third one from ever happening again.
Most "the site is down" tickets are really DNS problems wearing a costume. Here's the practical DNS troubleshooting workflow I use — how to read dig output, follow the delegation chain, decode SERVFAIL and NXDOMAIN, and stop blaming propagation for things that are actually caching, TTL, or DNSSEC failures.