What type of computing solution would be defined as a platform that is implemented within the corporate firewall and is under the control of the IT department?

A private cloud is defined as a computing solution that is implemented within the corporate firewall and is under the control of the IT department. This environment is dedicated to a single organization, allowing for customization and greater control over resources, security, and compliance with regulations. Due to its deployment within a corporate firewall, the private cloud can leverage existing infrastructure while providing the scalability and flexibility typically associated with cloud services.

In contrast, public clouds are provided by third-party vendors over the internet and are shared among multiple organizations, which means they are not exclusively under any single company's control. VLANs (Virtual Local Area Networks) are networking configurations that separate devices on the same network to improve performance and security, while VPNs (Virtual Private Networks) provide encrypted connections over the internet to secure data communications. Neither VLAN nor VPN pertains to cloud computing solutions in the same way a private cloud does.