Test on IP addresses, mask and subnets

Question 1: A common subnet mask of 255.0.0.0 indicates 16 network bits.

A. Yes

B. No

Explanation: The study materials state that the subnet mask 255.0.0.0 uses 8 network bits, not 16. The first octet consists of 8 ones, making it 8 network bits, and the remaining 24 bits are host bits.

Question 2: In CIDR notation, what does the number 'n' following the forward slash (e.g., /24) primarily indicate?

A. The total number of bits in the IPv4 address.

B. The number of bits that constitute the network portion of the IP address, starting from the left.

C. The number of bits that identify the host portion within the network.

D. The maximum number of hosts allowed in the network segment.

Explanation: The study materials state that in CIDR, the number 'n' specifies how many bits from the left of the IP address constitute the network portion. This is also explained in the example, where '192.168.1.10/24' indicates the first 24 bits are the network portion. The total number of bits in an IPv4 address is 32, not 'n'. The number of bits for the host portion is '32 - n', not 'n'. The materials do not mention 'n' indicating the maximum number of hosts.

Question 3: To calculate the broadcast address for a given subnet, all host bits of its network address are set to 1.

A. Yes

B. No

Explanation: The study materials state: 'To find the broadcast address, set all host bits of the network address to 1.'

Question 4: Subnetting contributes to a less efficient utilization of IP addresses by increasing overall waste.

A. Yes

B. No

Explanation: Subnetting improves IP address utilization. It allows for more granular allocation of addresses, which prevents waste that was common in classful networking where large blocks of IP addresses were often unused.

Question 5: According to the provided study materials, which formula correctly determines the number of usable host addresses within a subnet, and what do the variables represent?

A. 2^n - 2, where 'n' is the number of network bits, excluding the network and broadcast addresses.

B. 2^h - 2, where 'h' is the number of host bits, accounting for the reserved network and broadcast addresses.

C. 2^h, where 'h' is the number of host bits, with the network and broadcast addresses being usable.

D. 2^n + 2, where 'n' is the number of network bits, including the network and broadcast addresses.

Explanation: The study materials state that the formula for calculating the number of usable host addresses is '2ʰ - 2', where 'h' is the number of host bits. The subtraction of 2 explicitly accounts for the network address and the broadcast address, which are reserved and cannot be assigned to host devices.