Michael B. Smith is an independent consultant and a Microsoft Exchange Server MVP. He's been using Exchange since version 5.0 and working with messaging applications since 1981. He has a blog at theessentialexchange.com.
Many alternatives are available for implementing Exchange in your environment, including traditional deployment, virtualization, cloud-based solutions, and a combination of these approaches. To find the best solution for your organization, you need to consider the benefits and caveats of each option.
Every Exchange administrator should know some DNS basics. This includes understanding how DNS should be configured for Exchange and how to verify that DNS has been configured properly for your domains.