200-301 Question 85
Single answerYou are tasked with configuring a small office network. The network requires a subnet that can accommodate at least 50 hosts. The IP block assigned to you is 192.168.1.0/24. Which subnet mask should you use, and what would be the first usable host address in the subnet?
- A
Subnet mask: 255.255.255.224, First usable host: 192.168.1.33
- B
Subnet mask: 255.255.255.192, First usable host: 192.168.1.65
- C
Subnet mask: 255.255.255.192, First usable host: 192.168.1.129
- D
Subnet mask: 255.255.255.128, First usable host: 192.168.1.1
Show answer and explanation
Correct answer: B
Explanation
To accommodate at least 50 hosts, you need a subnet mask that provides at least 64 addresses (50 usable hosts + 2 for network and broadcast addresses). The /26 subnet mask (255.255.255.192) provides 64 addresses per subnet. The first usable host in the second subnet (192.168.1.64/26) is 192.168.1.65.
- A. Incorrect.
This subnet mask (255.255.255.224 or /27) provides 32 addresses per subnet, which is insufficient for 50 hosts.
- B. Correct.
This subnet mask (255.255.255.192 or /26) provides 64 addresses per subnet, which accommodates 50 hosts. The first usable host in the second subnet (192.168.1.64/26) is 192.168.1.65.
- C. Incorrect.
While this subnet mask (255.255.255.192 or /26) is correct, the first usable host in the third subnet is 192.168.1.129, which is not the correct range for the required subnet.
- D. Incorrect.
This subnet mask (255.255.255.128 or /25) provides 128 addresses per subnet, which is more than required. However, it is less efficient, and the first usable host in the range 192.168.1.0/25 is 192.168.1.1, which does not match the scenario.