Thank you! Is subnet A having the IP-address 292.168.10.32 and not 292.168.10.0 (ending in zero) not considered a mistake? I thought network addresses should end in 0 to indicate that they're network and not host addresses.

Thank you for your answer! What does $k'$ stand for in your notation?

"each time the machine halts and rejects" We don't have this information. The halting problem: $H = \left\{ \left \langle M \rangle, x \: \right| x \in L(M) \right\} $. Either $M$ accepts $x$ or it doesn't. If $x \notin L(M)$, $M$ either doesn't halt or it halts and rejects, but we can't tell which.