From the course: Cert Prep LPIC-1 Exam 102 (Version 5.0)

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Network masks and CIDR notation

Network masks and CIDR notation - Linux Tutorial

From the course: Cert Prep LPIC-1 Exam 102 (Version 5.0)

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Network masks and CIDR notation

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- With IPv4 addresses, there are four octets of eight bits each, making up a 32-bit number. In decimal, this ranges from 0.0.0.0 to 255.255.255.255 It's a bit clumsy to work with in decimal, so let's convert it to binary. The numeric range in binary is 00000000.00000000.00000000.00000000 to 11111111.11111111.11111111.11111111 This might not look better, but it'll make more sense when we start breaking up networks into sub networks. Initially, the network portion of an IP address started with a zero as its higher-order bit and used seven bits of the first octet for the network address. This means we had seven bits left for networks, which gave us 127 networks. The rest of the IP address space was used for hosts. Since we have 24 bits for hosts, we have around 16 million hosts. This was fine when we only had a few companies needing very large networks. But it became clear that we need more networks and they…

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