The summary `192.168.144.0/20` is advertised to a neighboring router. What third-octet range does this prefix cover?

### Why this is right A `/20` leaves four bits of the third octet within the network portion and creates a block size of 16 at that octet. Since the starting value is 144, the covered third-octet values are 144 through 159. ### The concept Prefix boundaries determine how a network address expands into a range. At the third octet, a block size of 16 gives aligned ranges such as 128 through 143, 144 through 159, and 160 through 175. The starting value 144 belongs to the 144-through-159 block. This is the address range represented by the summary, not just a single third-octet value. ### The other options - **B. 144 through 151**: this is an eight-value range, which is too small for a `/20` block at this boundary. - **C. 128 through 143**: this is the preceding 16-value block. - **D. 160 through 175**: this is the following 16-value block. ### Worked numbers - **Given**: prefix `/20`; starting third-octet value 144. - **Find**: the third-octet range. - **Formula**: block size at the relevant octet is 16. - **Solve**: the block begins at 144 and contains 16 values, ending at 144 + 16 - 1 = 159. - **Answer**: third-octet values 144 through 159. - **Check**: 159 - 144 + 1 = 16 values. ### Terms - **IP**: Internet Protocol. The addressing system used to identify network destinations. ### Remember A block of 16 starting at 144 ends at 159, not 160.