Question

Consider a subnet identified as follows: 192.168.31.0/26.

Using the IP ranges from this subnet, what is the IP network mask used by hosts on the subnet?
Use dotted-decimal notation for the answer.

255.255.255.192
255.255.255.224
255.255.255.128
255.255.255.0

Answer 1

255.255.255.192

Step-by-step explanation:

Given subnet : 192.168.31.0/26

This implies that there are 26 1-bits in the subnet mask. So the subnet mask is:

11111111.11111111.11111111.11000000 (26 1's)

Translating each segment into decimal representation:

11111111 = 2^7 + 2^6+2^5+2^4+2^3+2^2+2^1+2^0

= 128+64+32+16+8+4+2+1

= 255

11000000 = 2^7 + 2^6

= 128 + 64

= 192

So the overall subnet mask is : 255.255.255.192