When you're on an airliner and fly through layers of clouds, you see first-hand that they come in many forms \u2014 sometimes hazy, sometimes translucent and sometimes so dense that you can't see through them. In many ways, cloud computing is similar \u2014 there are lots of gray areas, and it's hard to know exactly what you might get from each cloud offering.The decision to pursue a cloud computing strategy is checkered with questions: What cloud vendor do you hire? What apps do you put in the cloud? Do you use a public cloud or a private cloud? Then there are the issues of security, availability and disaster recovery to consider.Taking the time to address those considerations is critical, says Bill Claybrook, principal of Concord, Mass.-based New River Marketing Research Inc. The more information gathering you do at the start, he says, the better your results will be when you finally implement the cloud strategy that best fits your needs. Here, Claybrook shares his list of the top eight questions CIOs should ask prospective cloud vendors.1. Can I see your data center? To know how secure your data and applications are going to be with a vendor, Claybrook recommends hitting the road. "If I ran a datacenter, I'd want to visit any prospective cloud vendor's facilities and ask them to show me what kind of environment they have, what their security controls are, and let me see what they've got," says Claybrook. "They'd have to convince me how it would all work."2. How do I move my apps to the cloud? CIOs often neglect to ask how they can actually move their apps and data to the cloud, says Claybrook. "Usually you send it over some kind of trusted network connection [such as a VPN], but you need to know how it's done with each vendor."3. How are my apps and data protected from other users on the same cloud servers? Don't make any assumptions about how vendors handle multiple users, also known as multi-tenants, on the same cloud servers, Claybrook says. Ask detailed questions about the extent to which your data and apps will be protected when running with those of other cloud customers. Claybrook recommends having each vendor show you how they segregate their customers' data and applications.4. Can I speak with some of your customers? Claybrook recommends asking for customer references. Speaking with customers will give you the opportunity to compare what the vendor has told you with actual customer experiences, he says. 5. Can I move an existing app from my private cloud to your public cloud without massive reconfiguration? This question is critical because your cloud vendor's infrastructure is likely completely different from yours, Claybrook says. Consequently, if you want to move an app out of your datacenter, there will likely be some conflicts. "The application has been built assuming the use of particular storage technologies, specific network configurations and specific management tools," says Claybrook. "You need to know if it's moved to a public cloud, where all of those things are probably different, how you can make it work."The vendor may provide tools that can make the migration go more smoothly, Claybrook adds. It also helps to find a vendor whose technology ecosystem is similar to yours. "Some cloud vendors support multiple databases and various forms of networking," says Claybrook. "You'll want your applications to perform at least as well in the cloud after it's moved as it ran in your datacenter."6. How do I get my data back? In the event you need to move your applications and data back into your data center (or to another cloud vendor), you need to know exactly where your data is stored and how to get it back, Claybrook says. You also need to be clear on your contractual obligations should you ever decide to terminate the relationship with the cloud vendor. For instance, you may owe the cloud vendor money if you terminate the contract, he adds."Getting the data back so you can use it is not always easy," says Claybrook. "Talk about this beforehand. That should be part of the contract negotiations."7. How do you address government regulations? Many businesses have to comply with state or federal regulations regarding consumer privacy and data. With that in mind, it's critical to know how your cloud vendor is handling your data so you can be sure you are complying with all of the regulations that affect your business, Claybrook says. \n"There are cases, due to regulations, where you don't want your data stored outside of some particular area, maybe a specific state and certainly not outside your country," says Claybrook. "What kind of guarantee can you get from your cloud provider that your data stays within a certain place?"Claybrook emphasizes that it's the customer's responsibility to comply with government regulations. "You have to be sure you are still in compliance once you move to the cloud," he says. "Make sure that this is part of your contract."8. What will I really pay? "When Amazon EC2 and other public clouds came along, the assumption was that running your applications on a public cloud was going to be cheaper," Claybrook says. "Now some people are finding out that it's more expensive than they thought, and some are trying to move back and build out their own datacenters. So you need to have really good cost estimates for running apps on the cloud versus running them on your own premises."Customers can get misled on price when cloud vendors leave details out of their cost estimates, says Claybrook. "Be sure to ask about everything you need. Don't assume anything," he says. "For example, ask if there are charges for transferring data over networks to the cloud. \nAsk a lot of questions. Ask the questions that you're hesitant to ask."Todd R. Weiss covers ERP, CRM, BI, Oracle, SAP, virtualization and cloud computing for CIO.com. He's also interested in a wide range of other fascinating IT topics, from open source to data centers and more. Follow Todd on Twitter @TechManTalking. And don't forget to join Todd in the CIO Forum on LinkedIn.com to talk with CIOs and IT managers about the things that keep them up at night. Email Todd at email@example.com.