What is the highest decimal value you can have for one byte in an IPv4 address?

In the context of an IPv4 address, each address consists of four bytes, and each byte can represent a value ranging from 0 to 255. This is because a byte consists of 8 bits, and with 8 bits, the maximum number of combinations is 2^8, which equals 256 different values. These values range from 0 (00000000 in binary) to 255 (11111111 in binary).

Therefore, when looking for the highest decimal value for one byte in an IPv4 address, 255 is the maximum value, indicating that the correct answer is 255.

The other options present numbers that are either too low, like 128, or exceed the limits of a byte, such as 256 and 512. Specifically, 256 is actually one more than the maximum value a byte can hold, and 512 is significantly larger than what a byte can represent. Thus, 255 is indeed the correct value, aligning with the representation capacity of a byte in the context of IPv4 addressing.