100-150 Question 74
Single answerYou are tasked with configuring a new subnet in your network using the IP range 192.168.10.0/24. The subnet needs to support up to 50 devices. Which subnet mask should you use to meet this requirement?
- A
255.255.255.0
- B
255.255.255.128
- C
255.255.255.192
- D
255.255.255.224
Show answer and explanation
Correct answer: B
Explanation
To determine the correct subnet mask, you need to ensure that the subnet supports at least 50 devices. Each subnet must also account for 2 reserved addresses (network and broadcast). A /25 subnet mask (255.255.255.128) creates a block of 128 IP addresses, with 126 usable for hosts. This is sufficient for 50 devices and is more efficient than choosing a /24 subnet mask, which would unnecessarily allocate more addresses.
- A. Incorrect.
255.255.255.0 (/24) provides 256 IP addresses (254 usable for hosts), which is more than necessary for 50 devices. While it is valid, it does not meet the requirement to subnet efficiently.
- B. Correct.
255.255.255.128 (/25) provides 128 IP addresses (126 usable for hosts), which is sufficient for 50 devices and more efficient than /24. This is the correct answer.
- C. Incorrect.
255.255.255.192 (/26) provides 64 IP addresses (62 usable for hosts). Although it is closer to the desired number of 50 devices, it does not provide enough usable IPs to account for network and broadcast addresses.
- D. Incorrect.
255.255.255.224 (/27) provides 32 IP addresses (30 usable for hosts), which is insufficient for 50 devices.