With a custom subnet mask of 255.255.255.248, how many usable IP addresses are available?

With a custom subnet mask of 255.255.255.248, how many usable IP addresses are available?

• A. 2
• B. 4
• C. 6
• D. 8

Answer: (C)

To determine the number of usable IP addresses available with a subnet mask of 255.255.255.248, it's crucial to first understand the subnetting concept and how it applies to IP addressing. The subnet mask 255.255.255.248 indicates that the first 29 bits (the binary representation of the subnet mask has 29 '1's followed by 3 '0's) are used for the network portion, while the remaining 3 bits are available for host addresses. To calculate the total number of IP addresses available within this subnet, you use the formula \(2^n\), where \(n\) is the number of bits available for host addresses. In this case, with 3 bits for host addressing: \[ 2^3 = 8 \] This means there are 8 total IP addresses in this subnet. However, when counting usable IP addresses, it's important to subtract 2 from the total: one address is reserved for the network (the first address in the range), and one address is reserved for the broadcast (the last address in the range). Thus, the number of usable IP addresses is: \[ 8 - 2 = 6 \] Hence, with a subnet

To determine the number of usable IP addresses available with a subnet mask of 255.255.255.248, it's crucial to first understand the subnetting concept and how it applies to IP addressing.

The subnet mask 255.255.255.248 indicates that the first 29 bits (the binary representation of the subnet mask has 29 '1's followed by 3 '0's) are used for the network portion, while the remaining 3 bits are available for host addresses.

To calculate the total number of IP addresses available within this subnet, you use the formula (2^n), where (n) is the number of bits available for host addresses. In this case, with 3 bits for host addressing:

[

2^3 = 8

]

This means there are 8 total IP addresses in this subnet.

However, when counting usable IP addresses, it's important to subtract 2 from the total: one address is reserved for the network (the first address in the range), and one address is reserved for the broadcast (the last address in the range). Thus, the number of usable IP addresses is:

[

8 - 2 = 6

]

Hence, with a subnet