Subnetting and CIDR Notation Flashcards
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What does CIDR stand for in networking?
Answer: Classless Inter-Domain Routing
CIDR stands for Classless Inter-Domain Routing, a method for allocating IP addresses and routing that replaced the older classful network system.
Which subnet mask corresponds to the /24 prefix length in CIDR notation?
Answer: 255.255.255.0
A /24 prefix means 24 bits are set to 1 in the subnet mask, which equals 255.255.255.0 in dotted-decimal notation.
How many usable host addresses are available in a /27 subnet?
Answer: 30
A /27 subnet has 5 host bits (32-27=5), giving 2^5=32 total addresses minus 2 (network and broadcast) = 30 usable hosts.
What is the network address for the host 192.168.10.35/28?
Answer: 192.168.10.32
A /28 mask (255.255.255.240) has a block size of 16; the subnets are .0, .16, .32, .48 — host .35 falls in the .32 subnet.
Which class of IPv4 addresses uses the default subnet mask of 255.255.0.0?
Answer: Class B
Class B addresses (128.0.0.0–191.255.255.255) use a default subnet mask of 255.255.0.0, providing a /16 prefix.
How many bits are in the host portion of a /26 subnet?
Answer: 6
IPv4 addresses have 32 bits total; subtracting the /26 prefix leaves 32-26=6 bits for the host portion.
What is the broadcast address for the network 10.0.0.0/8?
Answer: 10.255.255.255
The broadcast address is the last address in the subnet; for 10.0.0.0/8, all host bits are set to 1, giving 10.255.255.255.