By default, which adapter is typically used for virtual machines in vSphere?

The E1000 adapter is typically used by default for virtual machines in vSphere environments because it emulates the Intel 82545EM Gigabit Ethernet NIC. This adapter provides broad compatibility, allowing virtual machines to function in a variety of operating systems without requiring additional drivers. Its design allows for easy deployment and is beneficial for environments where no specific optimizations are required.

While other adapter types like E1000e and VMXNET3 offer enhanced features like better performance, lower CPU usage, and additional functionalities such as offloading capabilities, they may also require additional steps for installation and configuration, such as installing specific drivers in the guest operating system. In contrast, the use of the E1000 as a default option ensures that users encounter fewer compatibility issues right out of the box, making it an ideal choice for users who prioritize ease of use and compatibility across diverse operating systems.