Why Does the Internet Take Time to React When Something Changes?

You restart your router and for thirty seconds, nothing works — even though the connection is back. An engineer at a data center unplugs a cable and reconnects it, and traffic takes a full minute to return to normal. A major ISP fixes a network fault and customers are still reporting problems twenty minutes later. The fix happened. So why is the network still broken? The answer has nothing to do with anything being wrong. It's about how routing knowledge spreads — and what the network looks like while it's still catching up with a change that already happened.