100-150 Question 57
Single answerYou are tasked with configuring a new subnet for a small office network. The network requires up to 30 usable IP addresses for devices. You have been given the IP range 192.168.1.0/24. Which subnet mask would you assign to meet the requirement while minimizing wasted IP addresses?
- A
255.255.255.224 (/27)
- B
255.255.255.192 (/26)
- C
255.255.255.240 (/28)
- D
255.255.255.248 (/29)
Show answer and explanation
Correct answer: A
Explanation
To determine the appropriate subnet mask, calculate the number of usable IP addresses each subnet mask provides. A /27 subnet provides 32 total IP addresses, with 30 usable after reserving 2 for the network and broadcast addresses. This meets the requirement for 30 usable IPs and minimizes wasted addresses, making /27 (255.255.255.224) the correct choice.
- A. Correct.
This subnet mask (255.255.255.224 or /27) provides 32 total IP addresses, of which 30 are usable. This meets the requirement exactly while minimizing wasted addresses.
- B. Incorrect.
This subnet mask (255.255.255.192 or /26) provides 64 total IP addresses, of which 62 are usable. While this can meet the requirement, it wastes more IP addresses than necessary.
- C. Incorrect.
This subnet mask (255.255.255.240 or /28) provides 16 total IP addresses, of which 14 are usable. This does not meet the requirement for 30 usable IP addresses.
- D. Incorrect.
This subnet mask (255.255.255.248 or /29) provides 8 total IP addresses, of which 6 are usable. This does not meet the requirement for 30 usable IP addresses.