What does the prefix length in CIDR notation represent?
Think about how CIDR divides the IP address into network and host parts.
The prefix length specifies how many bits from the start of the IP address are used to identify the network. The remaining bits are for hosts.
Given the CIDR notation 192.168.1.0/26, how many usable IP addresses are available in this subnet?
Calculate 2 to the power of host bits, then subtract network and broadcast addresses.
/26 means 32 - 26 = 6 bits for hosts. 2^6 = 64 addresses total. Subtract 2 for network and broadcast, so 62 usable.
Which of the following CIDR blocks overlaps with 10.0.0.0/16?
Check if the IP ranges covered by the blocks share any addresses.
10.0.0.0/16 covers 10.0.0.0 to 10.0.255.255. 10.0.128.0/17 covers 10.0.128.0 to 10.0.255.255, so they overlap.
Which CIDR prefix represents the smallest subnet?
Smaller subnet means fewer host bits, so larger prefix number.
/22 has more bits for network than /20, /18, or /16, so it covers fewer addresses and is the smallest subnet.
Which pair of CIDR blocks can be aggregated into a single larger CIDR block without including extra IP addresses?
Aggregation requires contiguous blocks with matching prefix lengths and aligned boundaries.
192.168.0.0/25 covers 0-127, 192.168.0.128/25 covers 128-255. Together they form 192.168.0.0/24 exactly.