Given the following IP address - 20.54.23.3 and subnet mask - 255.255.255.0 choose the subnet ID and the broadcast address from that particular IP.

(A)
Subnet ID: 20.54.23.0
Broadcast Address: 20.54.23.255

(B)
Subnet ID: 20.54.0.0
Broadcast Address: 20.54.0.255

(C)
Subnet ID: 20.54.0.0
Broadcast Address: 20.54.255.255

(D)
Subnet ID: 20.54.23.1
Broadcast Address: 20.54.23.255

A is the correct answer. If the mask has only 255 and 0 then the process of finding the subnet ID and the broadcast address is straightforward.

Use the following steps for each of the four octets to find the subnet ID:

Step 1) If the mask octet = 255, copy the decimal IP address.
Step 2) If the mask octet = 0, write a decimal 0.

Use the following steps for each of the four octets to find the subnet broadcast address:
Step 1) If the mask octet = 255, copy the decimal IP address.
Step 2) If the mask octet = 0, write a decimal 255.