Before loading a site, your browser looks up its name in DNS — the internet’s phone book — to get an IP address. NXDOMAIN is the phone book’s answer for “that name doesn’t exist.” Either the name really is gone (typo, expired domain), or something between you and the phone book is giving a stale or wrong answer.
ipconfig /flushdns. Mac (Terminal): sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder. Then reload.chrome://net-internals/#dns → Clear host cache — Chrome keeps a separate cache from the operating system.Check, in order: the domain registration hasn’t expired; the nameservers at the registrar point where you think they do; the A/AAAA/CNAME records exist for both the root domain and www; and if you just changed records, wait — DNS changes can take a while to propagate, and negative answers get cached too. This site’s DNS Lookup tool shows what public resolvers currently return for a name.
If only one network (work, school) fails the name, its DNS may be filtered on purpose — that’s a policy, not a fault. If the name fails everywhere for more than a day and it isn’t yours, the site has most likely moved or closed; search for its name to find a new address.
Is DNS_PROBE_FINISHED_NXDOMAIN a problem with my computer? Sometimes, but not usually. The order of tests above separates them: if the site fails on a second network too, the name or its DNS is the problem, not your device.
How long do DNS changes take to show up? Minutes to a few hours in most cases. Old answers — including “doesn’t exist” — are cached for the time the domain’s settings specify, which is why flushing caches is on the list.