6 IPv4 Addressing and Subnetting Free Online FlashCards

What is an IPv4 address?

An IPv4 address is a 32-bit value written as four decimal octets separated by periods. Each octet ranges from 0 to 255.

How are network and host bits arranged in a subnet mask?

A subnet mask has consecutive 1 bits for the network prefix, followed by 0 bits for host addresses.

How many host bits does a /26 prefix leave?

A /26 prefix has 26 network bits and 6 host bits.

What subnet mask corresponds to /26?

The subnet mask for /26 is 255.255.255.192.

What flexibility does CIDR provide?

CIDR allows networks to use prefix lengths suited to their needs instead of relying on fixed address classes.

How are the host bits set in an IPv4 network address?

The network address has all host bits set to 0.

How do you calculate total and usable addresses in an ordinary subnet?

With $h$ host bits, a subnet has $2^h$ total addresses and normally $2^h - 2$ usable host addresses.

What is the usable-address exception for a /31 point-to-point link?

A /31 subnet on a point-to-point link can use both addresses as endpoints.

For 192.168.10.77/26, what are the network, usable range, and broadcast?

Network: 192.168.10.64; usable hosts: 192.168.10.65–192.168.10.126; broadcast: 192.168.10.127.

How many /27 subnets fit in a /24?

A /24 divided into /27 subnets borrows 3 bits, producing $2^3 = 8$ subnets.

How many usable host addresses are in an ordinary /27 subnet?

A /27 leaves 5 host bits, so an ordinary subnet has $2^5 - 2 = 30$ usable host addresses.

Which /27 subnet contains 192.168.10.142, and what is its usable range?

Network: 192.168.10.128; usable hosts: 192.168.10.129–192.168.10.158; broadcast: 192.168.10.159.