Why Your Website Works in Chrome but Not Safari: A DNS Caching Deep Dive

A cafe owner in Salthill rang me last month in a panic. "My website's down." I checked on my phone — loaded fine. She checked on hers — nothing. Her husband's laptop? Also nothing. Her daughter's phone? Worked perfectly. Same WiFi. Same network. Some devices could reach the site, others couldn't. Classic DNS caching issue, and it catches people out more often than you'd think. What actually happened She'd migrated her site to a new host the day before. The domain's DNS records were updated to point to the new server's IP address. But here's the thing — not every device got the memo at the same time. DNS doesn't update instantly. When you change a DNS record, the old IP address is cached at multiple levels: your browser, your operating system, your router, your ISP's resolver. Each cache has its own expiry timer (the TTL — Time to Live), and until that timer runs out, the device keeps using the old, stale IP. Her phone had cleared its cache recently (she'd restarted it that morning). He