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networks/traceroute-how-a-countdown-number-reveals-every-stop-between-you-and-a.md Traceroute: how a countdown number reveals every stop between you and a server Your data crosses a dozen machines on its way to a server, and you never see one of them. Yet a tool called traceroute lists every stop in… 5 min read · 23 Oct infrastructure/cron-schedules-five-fields-that-tell-a-computer-when-to-run-a-job.md Cron schedules: five fields that tell a computer when to run a job Want a computer to run a job at 3 a.m. while you sleep? On Linux and macOS, a program called cron does it, and each job is described by… 5 min read · 12 Oct networks/dns-lookups-why-a-website-is-slower-the-first-time-you-visit.md DNS lookups: why a website is slower the first time you visit Typing a name like www.example.com sets off a short chain of questions: a resolver asks a root server, then a .com server, then the… 5 min read · 11 Oct tools/what-does-1-2-3-mean-in-package-json-version-rules-you-can-try.md What does ^1.2.3 mean in package.json? Version rules you can try Open any package.json and you'll see versions like `^4.17.21` or `~1.2.3`. That little symbol is a rule for which updates npm may install… 5 min read · 8 Oct networks/how-does-example-com-turn-into-an-ip-address-dns-step-by-step.md How does example.com turn into an IP address? DNS, step by step Computers find each other by number, not by name. Before your browser can load example.com, it has to find the site's IP address, and… 11 min read · 1 Oct