More and more corporate data and software now runs in the cloud, meaning outside a business’s own data centers. Software that once ran on internal servers has pretty much flown the coop. If your company uses Salesforce.com, Dropbox, or Microsoft Office 365, you’re part of the great cloud generation.

Ideally, you won’t notice the massive, tectonic change underlying this shift from on-premises to cloud. But sometimes, alas, you will.

As was the case with the recent distributed denial of service (DDoS) attack that took down Dyn’s domain name services (DNS), which blocked many Internet users on the Eastern Seaboard from their favorite applications. And it wasn’t just Twitter twtr , Netflix nflx , and Reddit, but also more business-focused applications from Github, Zendesk zen , Zoho, Box box , and other services. (For further information, Gizmodo complied a comprehensive list.)

So ten years into this massive tech migration, what have we learned? Here are some takeaways from tech leaders who spoke at the Structure Conference this week in San Francisco.

The Companies You Depend Upon Depend Upon Others

The use of applications from Salesforce crm , Microsoft msft , and other companies that stream services over the Internet means you are dependent not only on those vendors, but on their partners as well.

It wasn’t Box’s fault that Dyn went down, but the lesson here is those big suppliers need to use more than one domain name service, said Lance Crosby, co-founder and CEO of Stackpath, a security startup. His company did not use Dyn, but it was hugely impacted by what happened to Dyn.

To be fair, Dyn recovered fairly quickly given the sheer size of the attack, which reportedly relied on millions of connected devices—most of which either were not password-protected or used factory default settings. But this was a very bad portent of things to come, said Crosby, who warned that the Internet is becoming a very dangerous place.

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Within a few years, it could become unusable, he predicted. “You’ll connect to the Internet only as long as it takes to transact business and immediately disconnect,” he said. That, clearly, is not the way we use the Internet now.

Don’t Forget the Dark Side of Disruption

Cloud services—including infrastructure from Amazon Web Services, Microsoft, and Google—can cut costs for tech companies and make them more flexible. But all those productivity gains impact others in negative ways. The people who used to reconfigure and maintain all those traditional server rooms and data centers are in less demand now. Automation means fewer people are needed for mundane tasks

Joyent chief technology officer Brian Cantrill pointed out that the impact of technology on people helped drive voters to Donald Trump. Cantrill’s post-election night talk outlined how those who are displaced by automation are not longer taking these huge changes lying down. As more jobs in healthcare, education, and transportation become automated out of existence, there will be more disaffected, under-, or unemployed people on the street. If they are not retrained for other jobs, that means trouble not only for these citizens, but also for businesses looking to sell to them.

Some Things Never Change

There were the usual arguments and debates over whether moving data and software to AWS, Microsoft Azure, or some other public cloud is always the cheapest, best option. For uneven, “spiky” workloads that change by the week, day, or hour, it makes sense to use flexible public cloud services because customers pay only for what they use. Why buy a pricey server that you have to power, maintain, and upgrade yourself if you use 10% of its capacity 90% of the time?

But for stable production workloads, it can be cheaper to run your own data center, skeptics continue to insist. One Structure attendee, who did not identify himself, asked AWS product strategy general manager Matt Wood about this. The questioner said that for a big stable set of tasks, it can be four times cheaper to run in-house versus AWS. The questioner’s contention is backed up by the fact that Dropbox, which relied heavily on AWS to store millions of customer files, has moved 90% of that work into its own data centers. Wood offered to go over the math with the questioner, and the session ended.

Risk-Averse Companies Are Now Moving to the Cloud

Microsoft cloud chief Scott Guthrie said even the most conservative financial institutions, the too-big-to-fail banks are now aboard the cloud bandwagon. These are the same sorts of companies that have shied away from the cloud because they feel they don’t have control of their hardware.

Nowadays, Guthrie claimed 75% of the largest banks and 90% of the Fortune 500 overall now use Microsoft Azure in some capacity. AWS’s Woods also noted how Capital One cof , an early cloud advocate among banks, uses AWS to power its mobile apps.

Keep Your Data Safe—And in Many Places

There is an adage in modern computing: Never have one point of failure. And that is as true when it comes to your personal data as anywhere, remarked Paula Long, CEO of DataGravity, a New Hampshire-based data storage specialist.

Keeping multiple (encrypted) copies of your important data is table stakes for everyone from now on.