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Networking Fundamentals · Foundational

Octet

A group of 8 bits; an IPv4 address contains four octets.

Definition

An octet can represent decimal values from 0 to 255. Networking prefers "octet" over "byte" because historically byte sizes varied between systems. Subnetting work is usually done one octet at a time, focusing on the octet where the mask boundary falls.

Example

In 10.1.2.3 the third octet is 2.

Exam tip

The "interesting octet" is the one where the subnet mask is neither 255 nor 0.

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