Why isn't a new DNS record immediately available globally?

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http://serverfault.com – Simple case: I register a domain Specify 2 name servers Setup web hosting Visit the domain in my browser At this point the browser tells me it cannot resolve the host, presumably because the DNS record has not propagated yet (i.e. cleared collective DNS server caches)... This is strange to me though. Why isn't the domain immediately resolved in the browser? Why can't the browser/router/name-servers simply forward the DNS query to the authoritative server instead of returning the cached query results which seems to be "Could not find host, yourNewDomain.tld" I am probably greatly misunde (HowTos)