In a Class A Internet address, which of the following network numbers are reserved?

The correct answer identifies the reserved network numbers for Class A Internet addresses, specifically 0 and 127. In the context of IP addressing, certain network numbers are designated for specific purposes.

The network number 0 is reserved for use in routing protocols and is not assigned to any specific network. This allows it to be used to refer to the default route. The network number 127 is reserved for loopback addresses, which are used for diagnostics and local testing on the same host. When data is sent to this range, it is directed back to the originating device, allowing for self-test capabilities.

Understanding these reserved network numbers is crucial for network engineers and professionals, as misuse of these addresses can lead to routing issues or network conflicts. The other options provided include numbers used for different classes of addresses, or not strictly reserved for the purposes defined in the question. This highlights the significance of knowing the proper usage and assignment of network numbers in the broader context of IP addressing.