BOSTON (AP) — An outage at a little-known firm that knocked a lot of top internet destinations offline, disrupting business and leisure for untold millions globally, was quickly resolved Tuesday. But the incident raises questions about how vulnerable the global internet is to more serious disruption. While companies such as Fastly, the affected provider, invest heavily in reliable service, it’s overly optimistic to expect flawless, always-on access. Outages are not all that common, but can sting badly if companies and individuals aren’t prepared. An important question is how much of our crucial data we should entrust to the cloud.