Question 38

The given subnet mask is 255.255.255.252 (or /30 prefix length).
In binary, the last octet of the mask is $252 = 11111100_2$, which leaves $2$ bits for the host ID.

The block size (subnet increment) is $256 - 252 = 4$.
Let us determine the subnet boundaries in the fourth octet:

• Subnet 0: 100.10.5.0 to 100.10.5.3 (Usable hosts: .1 and .2)
• Subnet 1: 100.10.5.4 to 100.10.5.7 (Usable hosts: .5 and .6)
• Subnet 2: 100.10.5.8 to 100.10.5.11 (Usable hosts: .9 and .10)

Now examine the three given IP addresses:

• $M = 100.10.5.2$: belongs to Subnet 0 (100.10.5.0/30).
• $N = 100.10.5.5$: belongs to Subnet 1 (100.10.5.4/30).
• $P = 100.10.5.6$: belongs to Subnet 1 (100.10.5.4/30).

Thus, $N$ and $P$ belong to the same subnet (100.10.5.4/30), while $M$ belongs to a different subnet. Therefore, "Only N and P belong to the same subnet" is true.