Ep 7: Opening a website = sending a letter

Episode 7 of 448 · Tip

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In one sentence: opening a website is like posting a letter: you write a name, DNS looks up the real address, the server reads your request and sends back the page.

Step by step

1. You write the address: you type loopnotes.com in the browser.
2. DNS is the address book: computers don’t use names, they use numbers called IP addresses. DNS turns loopnotes.com into something like 203.0.113.10.
3. The letter is delivered: your browser sends an HTTP request to that IP address.
4. The server replies: it sends back the page (HTML, images, data).

Why this matters in DevOps

Most “the site is down” incidents are somewhere on this path: a wrong DNS record, a server not listening on the right port, a firewall blocking the request, or the app crashing before it can reply. Knowing the path tells you where to look.

Note

203.0.113.x is a range reserved for documentation examples, so we use it instead of real servers’ addresses.