madeeasy test series

Question

answer given as 255.255.255.254  how it is correct please check??

Comments

never seen of borrowing, can't confirm if it is valid, if we can use it then it's simple, still 255.255.255.254 can't be true. we need network bits as it is.

---

ok but check solution I commented it is correct or not.

---

yes i think is ok, you have $9$ bits for host so $510$ hosts required also $510$. Should be ok. DBA only hosts bits are $1$. Should be ok.