Which of the following is a reserved IP address in VPC subnets?

In a Virtual Private Cloud (VPC) subnet, the first address is reserved for the network itself and is not assignable to instances or other resources within that subnet. This address is known as the network address and acts as an identifier for the subnet.

The reserved first address is crucial for routing and communication purposes, allowing devices within the subnet to understand how to reach each other. Each subnet is identified by its network address, which is derived from the IP address range defined for the subnet.

On the other hand, while the last address in the subnet is also reserved (known as the broadcast address), the focus of the question is specifically on the network address, which is the first address in a subnet. The other options regarding the third address, second address in another subnet, and more do not relate to reserved IP addresses in the same foundational way as the first address does. Thus, recognizing the significance of the first address within the context of subnetting is essential for effective network design and management in cloud environments.