100-150 Question 71
Single answerA network administrator has been assigned the IP address 192.168.10.0/24 for a network. They need to divide this network into four equal subnets. Which of the following subnet masks should be used, and what is the first usable IP address of the second subnet?
- A
Subnet mask: 255.255.255.224, First usable IP: 192.168.10.33
- B
Subnet mask: 255.255.255.240, First usable IP: 192.168.10.17
- C
Subnet mask: 255.255.255.192, First usable IP: 192.168.10.65
- D
Subnet mask: 255.255.255.192, First usable IP: 192.168.10.64
Show answer and explanation
Correct answer: C
Explanation
To divide the 192.168.10.0/24 network into 4 equal subnets, the subnet mask needs to be 255.255.255.192 (/26), which provides 4 subnets with 64 IPs each. The subnet ranges are 192.168.10.0-63, 192.168.10.64-127, 192.168.10.128-191, and 192.168.10.192-255. The first usable IP of the second subnet (192.168.10.64-127) is 192.168.10.65, as 192.168.10.64 is the network address.
- A. Incorrect.
Subnet mask 255.255.255.224 would divide the network into 8 subnets with 32 IPs each, not 4 subnets. The first usable IP of the second subnet would not be 192.168.10.33.
- B. Incorrect.
Subnet mask 255.255.255.240 would create 16 subnets with 16 IPs each, which is incorrect as the goal is to create 4 subnets.
- C. Correct.
Subnet mask 255.255.255.192 divides the original /24 network into 4 subnets with 64 IPs each. The first usable IP of the second subnet would be 192.168.10.65.
- D. Incorrect.
While the subnet mask 255.255.255.192 is correct, the first usable IP address of the second subnet is not 192.168.10.64. That is the network address of the second subnet, not a usable IP.