SHA-256 is a well know hash function that creates digests of 256 bits. This means that the size of the digest space is 2^256 (or at least it should be), ie, the range of the digest space is:
0x 00 00 00 ... 00 00 00
0x FF FF FF ... FF FF FF
However, is there any kind of limitation in the SHA-256 algorithm that would not allow a specific range of digests?
0x 00 00 00 ... 00 00 00 and
0x FF FF FF ... FF FF FF are two possible digests for SHA-256 or it is impossible to exist a message that would hash into those values?